Review: the best duplicate/similar movie finder and cleaner software

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Nowadays most people use Netflix or similar streaming services for watching movies, but many old hands have sizeable older movie collections, brilliant classics you won't find streamed anywhere. No matter how you have amassed the movies, whether from old DVDs or downloaded, chances are you have several copies of many of those classic movies. If you think that the average movie has a file size over 1GB, you don't need many of those duplicates to choke up your hard disks. To tidy up your collection, save space and keep the best quality version of each movie, you need a duplicate detector tool, but how do you pick one? There are 102 alternatives to i-DeClone for Windows 7/10/11, both free and paid. This review will help you choose the best duplicate movie cleaner software.

Clearly the author is biased, but this review is objective. The most popular shareware programs that claim to deal with near-duplicate movie files are included, and their performance is measured on a fixed set of video files (movie collection library). We believe that the data are representative, almost scientific :) You are welcome to try your own movie library for duplicates — you should find the same results more or less, relatively speaking.

How do you discover near-duplicate video?

The technology behind duplicate file software is quite simple, almost trivial. You just examine all the files in your hard disk byte-for-byte, and discover all 100% identical files. This is fast and safe, but will not work very well for your movie file collection. Video is encoded compressed in various formats (along with its audio streams), in containers such as Matroska MKV, the old Audio Video Interleave (AVI) file, MPEG-4 (think MP3 but for video) and many more. Each container allows multiple resolutions (720p, FullHD, UHD etc) for increased movie quality (and byte size!). So a movie that you or me would instantly recognize, is hard to tell looking at the raw bytes stored in the file.

Recognizing movies calls for specialized software that can decompress and extract the video and audio streams from the movie file, then use a number of algorithms to compare them and discover similar movies. Some programs compare a succession of thumbnails (frames) using similar image detection methods, others focus on the soundtrack and use audio fingerprints to align and compare the audio streams. Such visual or audio algorithms can be used to compare movies, and see through differences in video resolutions, frame rates and dimensions, soundtrack loudness etc, to identify visually identical files — as opposed to binary-identical.

Some simpler duplicate files software ignore the audio/video content and try to find similar movies using file attributes like the name and duration. This is next to impossible for movies, where there is no universally accepted tagging system (like ID3 tags for MP3 music). Take for instance the following 2 video files. It is the same movie, but the file sizes and durations vary slightly, one is widescreen HD and the other 720p — still they represent the same movie!

Name								Size	Length		Frame width	Total bitrate
Batman.V.Superman.Dawn.Of.Justice.2016.1080p.BluRay.x264.mp4	2.79GB	03:02:33	1920		2184kbps
5t6783456.avi							2.62GB	03:02:30	720		2056kbps

What we need therefore is software that can find movie content duplicates, allowing for differences in HD resolution and file formats (WMV,AVI,MOV,ASX,MKV,MP4,ASF,MTS,TTS...). Media files need a computer program that can understand the video, not the raw bytes stored in them. The bytes may differ, even the picture quality itself slightly, but video-aware software will detect the similarity, almost as a human movie watcher would.

Most of the aforementioned 102 duplicate cleaners are not "movie savvy". I have narrowed it down to just six (6) computer programs (for Windows 7/10/11) that analyze the movies for similarity and will find video duplicates, which in alphabetical order are:

I will also consider another popular program called Auslogics duplicate file finder, just to show you how "naive" duplicate finders are not up to the task of discovering duplicate movies. Some of these programs are free or open source, and some shareware with free trial, so you would expect a decent quality in departments such as:

Before we begin the Video Clone Olympics, here's a table summarizing the main contenders for the title of Best duplicate video detective Windows software. Some are specialized for similar movies, others can handle also similar music and images. 64-bit programs are capable of handling huge media collections (32-bit programs are limited to 2GB memory)

Name/Website Version   Price  
(US $)
size (MB)
64 bit   Audio   Video   Images Notes  
  ■ Czkawka [CZK] 5.02 45.6 open source
requires ffmpeg
  ■ Duplicate Media Finder [DMF] 9.01 $46 26.6
  ■ Duplicate video search [DVS] 2.3 $30 15.5 separate programs
sold for music etc
  ■ i-DeClone [IDE] 1.54 $30 2.3
  ■ Video comparer [VCO] 1.07 $30 14.3
  ■ Video duplicate finder [VDF] 1.0 (?) 65.7 open source
cross platform
  ■ Auslogics duplicate file finder [AUD] 10.0 16.7 scans bytes, not video  

Information correct as of 18-Feb-2023

Typical workflow for finding and removing duplicate files

The workflow of all duplicate file removers more or less comprises 5 basic steps:

  1. Choose where to search. Define the search scope in certain folders or your entire PC and attached hard disks and other devices like phones.
  2. Choose what and how to search. We are searching for movie files; there are many search options that affect the speed and quality of the results. For this review we concentrate on similar video content, and the most important parameter is the similarity tolerance, a percent that shows how much similar 2 movie files should be to be considered duplicate. Lowering the similarity threshold will catch more duplicate movies but will also produce false positives, films that are completely different.
  3. Wait for results and preview. Audio/Video fingerprint scanning is slow by nature, but you don't need to sit on top of the duplicate scanner while it is searching. Once the results are in, you examine them to make sure the duplicate groups are correct. If you find any mistakes (false positives) in the results, you can remove the wrong files from further processing.
  4. Choose what to keep and what to remove. Once the search is finished, duplicate files are grouped together and offer a way to choose what is kept and what gets deleted. Mostly this is done using checkboxes. Manual selection is impractical when many duplicates are found, so programs offer various automatic ways to choose what gets deleted, e.g. the lowest resolution films, or the smallest file sizes (poor picture quality)
  5. Clean up marked items. Finally we want to remove duplicates and free up the hard disk space. This is either done by deleting the duplicate files, or replacing them with hard/symbolic links, which are like file shortcuts that don't take up much space. Some programs allow moving the duplicates in a separate folder, although I don't see the point — other than perhaps as a temporary measure. The goal is freeing up disk space and reducing junk and clutter from our movie collection.

    We are talking about similar movies, but what we are really after is identical films. We are not trying to find Star Wars episode IV similar to episode V, we want to see if we have Star Wars episode IV more than once in our collection. "Similarity" enters the picture because no 2 movie files are byte-identical, on account of resolution, quality and such parameters.


Czkawka is a free open source tool with multiple functions, including searching for similarly looking video files. According to the website:
...Multi functional app to find duplicates, empty folders, similar images etc. ... Czkawka is written in Rust and it aims to be a faster alternative to FSlint or DupeGuru which are written in Python

Czkawka main window

As a multi-platform tool (runs on Windows, Linux and MacOS), Czkawka's user interface has an unfamiliar look for Windows users, matching the weird name (apparently it means hiccup in Polish). The window design is tasteful but the font is too small (almost unreadable) and there is no obvious way to make it bigger.

But once you look around and find your bearings, it is straightforward to use. Its main strength is finding similar images; video similarity is based on analyzing video frames as images. The leftmost panel has many function modes, we need to select Similar videos, add a few folders to scan for movies, adjust the rather confusing similarity bar to the left (higher similarity) and click on Search button.

Duplicate movie results take their time to show up, and when they do they are organized in indented strips of similar movies as you can see in the window snapshot above. You cannot choose any file details like video duration or similarity %, and neither is any video preview available, so it is hard to work with the duplicate movie results, double checking for mistakes and false duplicates. Use the checkboxes to mark duplicate files manually or use Select button for automatic marking based on size (quality) or date (older or newer film). Then use one of the cleanup command buttons to either delete duplicate movies or create hard or symbolic links to save space.

Czkawka is a jack of many trades in disk cleanup, but it definitely isn't a master of similar movie files. It falls into an elementary duplicate video trap, examining the beginning of each movie, so it finds all movies e.g. produced by Disney or 20th Century fox "identical" (because they all start with the same introductory clip!). Therefore most of the results are wrong, and any correctly identified duplicate movies are lost in a sea of false positives.


I read many positive reviews on Czkawka, so the program must be doing something else very well (similar photos?) — but for video similarity it is a poor contender. It is free and open source, so the team may improve the video similarity algorithm eventually.

Free and open source

Smart looking, functional GUI


Too many false duplicates

No video file details or preview

Duplicate Media Finder

Duplicate Media Finder (finds and deletes duplicate files) will, according to their website:
As with image or audio files, Duplicate Media Finder analyses the content of video files. Our software can identify similar films among a multitude of formats (3g2, 3gp, asf, asx, avi, bsf, divx, f4v, flv, m2p, m2v, m4v, mkv, mov, mp4, mpeg, mpg, ogv, ts, vob, webM, wmv, xvid). DMF can therefore find movies that are visually very close (even resized,...) without being identical

Duplicate Media Finder main window

We have seen Duplicate Media Finder before; it is very good in detecting similar music, and it has a very good similar movie file search engine too. As you can see from the pic above, the user interface favors design over ease of use. The oddness of the UI hampers usability at least until you realise that some buttons are really toggle switches, e.g. to select what to search for — they go partially green when active.

There are kind-of-tabs for search setup (where and what to search). There are few options offered for tweaking, but they are the most useful ones, so no complaint there. For our review the required options are search for similar media (then Video files), and all the other criteria aren't required (they are well hidden from view). A sensitivity trackbar adjusts the similarity tolerance. You select folders to scan using a checkbox-enabled folder tree, then click Start button and wait for the results.

The duplicate movie files found (results) tab is eccentric, showing thumbnails organized in rows, each row holding a set of duplicate films. Perhaps this display mode is useful for image thumbnails, but for video it is wasting space and hiding information about the duplicates involved. The first column is the master file, but it's not clear what criteria are used for the automatic choice. Managing results is clunky, done through the context menu. A glaring omission is the lack of checkboxes to permanently mark duplicates. Selecting items with the mouse is fragile, one wrong click and you lose all the selection! And are there no means for filtering the results? Where is the Delete button? Are we supposed to delete duplicate files one by one with the context menu?

It is a pity really, because the this program's duplicates search engine is quite fast and does no mistakes. Apparently they make use of all the available cores and processors, and it shows. It would probably be even faster if they included a 64-bit version. Its free trial mode is frugal (hiding movie file names), but with this kind of tool that's used infrequently, I can't blame them for being over-protective.


If Duplicate Media Finder was a movie, I would have thought that they ran out of money midway through the production. It has an excellent part for discovering similar media files, but it is almost unusable as a cleaner of duplicates, you may as well manually delete duplicates one by one. And nobody has time for such software, sorry. Perhaps their main audience is people that deal with pictures and thumbnails?

Finds duplicate music, video and images

Fast and reliable fingerprint algorithm


Quirky interface

Poor duplicate file management

Duplicate Video Search

Duplicate video search — find and remove duplicate movie files by Bolide software can, according to their website:
...other video detection apps concern themselves with analyzing surface qualities like filename or duration, DVS can find similar videos by digging deeper. Videos can be saved as different formats, at different resolutions, using various compression and DVS will still know whether they are essentially the same. The bigger your collection, the more time (and space!) you'll save using the Duplicate Video Search

Duplicate Video Search main window

Duplicate video search is a very focused piece of software, doing just duplicate movies, so it is very simple to use. All the controls can be seen in a single window with a toolbar, a big pane for the results and a side panel with scan options. It would be nice if this sidebar could be minimized after the search as it just stands in the way — we need space to see more results. The available tweaks are few but to the point.

First we add a few source folders to scan for movies, adjust the sensitivity factor to a small number (apparently it is the inverse of similarity, small sensitivity equals large similarity level). It is very important to add the recommended 180 seconds skip so we won't mis-identify "identical" movies on account of their beginning (which will be the same intro clip if we are scanning TV series episodes for example). Then click Search button to start the scan.

Although it isn't possible to pause a movie search, results come in very quickly, for this type of computationally intensive video comparison task. Clearly DVS uses video frames to locate similar movie files, and it presents a series of video frames in the results pane, which immediately tell you if a duplicate movie group is correct or false positive. The duplicate groups are clearly demarcated and can be collapsed. Some basic video information is also shown like frame size, duration and file size. Although file paths are hidden in free trial mode, I could tell the results exactly by their movie attributes. So I can tell you that most of the results are genuine duplicates, except for the 4 mistakes seen in the window snapshot above.

Duplicate video search automatically ticks the smallest files for removal (keeping the highest quality video), but there are no other duplicate marking options. If you need e.g. to keep the smallest files or any other marking logic, you are on your own, manually ticking boxes. In fact the program offers no options whatsoever, other than what can be seen in the side search options panel. Delete is the only cleanup option offered.


Duplicate video search has a good video fingerprinting algorithm that discovers duplicate movies quickly and with few mistakes. It is rather frugal in terms of marking and cleanup options.

Very strong video fingerprinting

Focused for similar movie file cleanup


Parsimonious in terms of options

Difficult to work with many duplicate files




i-DeClone is our own product that cleans-up duplicate and similar files, including movies. According to the website it:

...can recover the space wasted by identical files stored many times, or similar versions of the same information (e.g. similar photos), using advanced AI algorithms. The scan process is accurate, reliable and fast
i-DeClone is industrial-strength, built to handle thousands of duplicate files and folders

i-DeClone main window

i-DeClone began its life as a tool inside our xplorer², so it feels almost as a file manager. Its user interface is spartan but easy to use, because it hides its complexities well, while at the same time allowing expert users to go deeper if they so desire. It is a generic duplicate file management tool, that finds duplicate and similar music, videos, office documents, photos, e-books and even whole folders.

The UI comprises just a toolbar, having buttons dealing with the main steps of the workflow. Some split-buttons show a drop-down menu when clicked on the arrow. Click on Start scan to begin a new search, and set the type to Movies, add some folders to scan, then click on find similar files — that's all the information required. i-DeClone shows a summary of what is about to happen and guides you all the way to marking the duplicate movie files discovered.

Similar video results are shown in a list like windows explorer, each set of similar files in its own group. i-DeClone shows a thumbnail and relevant video attributes (frame size, bitrate, duration) and the similarity % of each group (high numbers mean good matches). Right click on the column header to choose additional file or video properties to see (300+ windows system properties are available). There's an embedded windows media player to watch the movies, ensuring they are correctly matched.

Use the checkboxes or Mark wizard to mark duplicate files for removal, using date or quality criteria. If you sort e.g. by Length (duration), you can easily mark the longest or shortest movie using Mark first in group option. The quickfilter box on the toolbar can filter the results by text appearing in any field, be it filename, path or bitrate. i-DeClone can manage thousands of duplicates in this way. For Clean-up you can opt for deletion to save space, or create hard or symbolic links. You can even save the results and work with them later.

i-DeClone lets you revise a duplicate files scan, e.g. using a different similarity threshold on the same video files. So if you happen to find too few hits, or too many false duplicates, you can quickly amend the search, using the files already examined and cached in memory.


i-DeClone packs lots of AI-driven power to discover any kind of duplicate files, be it movies or office documents. The interface is simple and explorer-like but very ergonomic. As you will see in timing data section it discovers many near-duplicate movies with the best performance in terms of CPU effort.

Complete solution for all duplicate file types

Discover many similar films in record time


Not very focused for duplicate movies

It could use a GUI facelift

Video Comparer

Video comparer — find and remove duplicate videos by content, written by Eric Bohain, can, according to their website: able to detect quickly duplicate videos with image transformations (included scaled, cropped, rotated, …) and time shifted (included division into multiple clips). The comparison powered by an robust “video fingerprint” technology considers only the content of videos, not the file attributes (name, size, …).

Video Comparer main window

Video comparer is another movie-only duplicate file detection, analysis and cleanup computer program. Its interface is very ergonomic, as you can see there's a folders area to pick up where to search (including network locations), then hit play button to get things going. There are scan settings to tweak but most of the defaults seem to work ok (or as bad as anything else I tried :). There doesn't seem to be a way to specify a minimum similarity level though, VCO reports both high and low similarity movies in its results, which is not very useful.

Duplicate movie groups discovered are presented with different colored background, and include plenty of relevant movie attributes (codec, bitrate, similarity etc), as well as video frame thumbnails properly aligned to demonstrate the successful similar movie match. Marking duplicates is achieved using manual tickboxes or its configurable autoselect command, that can mark for deletion the longest or shortest movie duration, the highest or lowest resolution quality and so on. For cleanup you get to delete or move duplicates into a folder.

On the negative side, Video comparer is by far the slowest of the duplicate movie scanners in this review, using its recommended Standard scan mode (I didn't attempt to use their "slow" Thorough and Full scan modes). It also generates too many false duplicates. Our findings thus contradict a benchmark comparison published by the maker of VCO, comparing the performance against 2 of the contenders in the present review (DMF and DVS) on a set of YouTube videos.


Video comparer is rather slow, and seems to get confused by video frame similarities of otherwise unrelated videos. I don't know whether there are some extra features in the full (paid) version, but the free trial had severe scanning problems.

"Just right" balance of video scan settings

Intuitive presentation of duplicate movies


Very slow to find duplicates

Too many mistakes

Video Duplicate Finder

Video Duplicate Finder is another free and open source computer program. According to their website:
Video Duplicate Finder is a cross-platform software to find duplicated video (and image) files on hard disk based on similarity. That means unlike other duplicate finders this one does also finds duplicates which have a different resolution, frame rate and even watermarked.

Video Duplicate Finder main window

Reading cross-platform and free open-source, you can deduce the unfamiliar user interface style and the difficulty installing this tool — but at least the price is right! Finding out what to download from github is always a challenge. You get a ZIP archive which you extract and find the main program to run. VDF requires ffmpeg as well, so that's another set of installation headaches. Definitely not consumer grade!

Video Duplicate Finder can do both similar videos and images, but we only require duplicate movies so make sure you untick include images from Settings tab. While there, you can add the folders to scan. I left the similarity percent to its default 95% value, then switched to the main Scanner tab and click on Scan button to get the search going.

Duplicate movies are presented in groups, combined with a collapsible tree node that hides an entire duplicate group. The fashionably dark interface doesn't help separating the groups visually. Extra geek credits go for using CLSID numbers as tree group node names (!) to keep movie-collectors-cum-geeks happy :) The results list includes a video thumbnail (one frame) and relevant video information like duration, frame resolution, even audio channels samples per second. You can filter results by path and similarity, and automatically tick boxes for duplicate movies to be removed by date/size/quality and even using excel like formulas such as arg.ItemInfo.IsImage && arg.ItemInfo.SizeLong > 3000 if you can get your head round such things.

There is no movie preview available but you can double click to open a movie in your default media player. I get the feeling that the program was originally designed for duplicate photos, despite its name. For example you can press ALT+C keys to compare 2 videos as large thumbnails. You get a few wrongly identified duplicates, which you can remove from further consideration using the context menu Mark as not a match. Once you have weeded out the false duplicates, you can delete the real duplicate movies or create links to save hard disk space.


Video Duplicate Finder is a good and free tool for finding duplicate films, if you manage to install and set it up (not everybody is a computer geek). It has a fast and accurate movie search engine that does only a few mistakes.

Free and open source

Fast similar movie file search


Difficult to install and set up

Not built for Average Joe consumers

Auslogics duplicate file finder

Duplicate File Finder for Windows by Auslogics Labs is, according to their website:
...the easiest way to sort through images, music, videos and other personal files to remove duplicate copies and free up disk space
The software uses intelligent algorithms to compare not only file names, but also contents to ensure no false search results

Auslogics duplicate finder window

This software isn't in the same league as the other duplicate scanners in this review, it is included to demonstrate that you need specialized tools for video similarity — a task Auslogics duplicate file finder falls well short of.

The user interface is simple and smart. First you use a tickbox-enabled folder tree to pick up folders to scan (you cannot choose network folders, only local media). Then you select the type of duplicate files to search for; all file types are allowed from Images to Audio and Video and everything else. You ca use a little wizard (Next button) to specify more search criteria that filter out e.g. small or huge size files. Or just click on Search to start the scan.

And then... nothing happens at all, because AUD scanner cannot find any duplicate movies from the test case. Zippo. It can only recognize simple duplicates with exactly the same name or same byte content, and as we have explained this is a dead-end approach for similar movie files. This kind of tool would only pick duplicate movies that you happened to have saved exactly identically in a few locations (same name, file format and everything). Which I suppose can be useful but it will not help cleaning up your movie collection thoroughly.

Had it found any duplicates, it presents them in a standard fashion, striped bands for each duplicate group and checkboxes to mark duplicates for removal. There is a built-in preview panel too. A selection assistant helps you tick duplicates quickly to be eventually deleted, either to the recycle bin or permanently.

This duplicate file finder is free for all uses. At this price one must not be too fussy or expectant. Naive duplicate file checkers have a use. The program does try to upsell you some of Auslogic's premium tools — developers must eat too!



Professional UI design


Cannot find similar movie files

Requires elevation to run (why?)

Duplicate movie scanner performance results

We have reached the essence of this comparative review, performance data on the job of actually discovering duplicate movie files. Which program out of the above 7 will find the most duplicates without making too many mistakes, and in reasonable time? All duplicate finders were tested on the same set of 720 movies and TV series episodes, a mixture of mostly AVI and also MKV and MP4, a real life video collection totalling 570GB in size. Duplicate films hide in the guise of different encoding formats (MP4 vs MKV), different resolutions (sampling quality), and slightly different lengths (on account of variable silence at the beginning of a movie).

Between them, these programs found 37 duplicate films; the most similar movies were discovered by everybody, whereas some borderline-similar movies (e.g. director's cuts, audio dubbed) were discovered only by a few programs (and each program found a different set of those films, according to the similarity algorithm used). None of the reviewed software got all of the duplicates right, but some fared better than the others.

The test rig for running the timing experiments was a Windows 11 VM with all the latest video codecs. If you'd run the same test, you wouldn't have found the same results, but the relative performance of the duplicate detector engines should be more or less the same. The cache of all software (if any) was disabled to compare the raw efficiency on fresh data (movie files)

Default "out of the box" properties were used for all duplicate finder software, unless they didn't work properly (see the notes section). I always picked a scan option that examined the content for similarity, using picture frame matching or audio signatures, at default similarity tolerance levels. Here are the timing results of the comparative test: (best results highlighted in green and worst in red)






  ■ Duplicate films discovered 16 33 25 31 15 25 0
  ■ False positives (mistakes) 40 0 4 0 26 8 0
  ■ Total scan time in minutes (MM:SS)   23:19 17:07 5:27 6:09 24:33 8:30 0:01
  ■ Throughput rate (duplicates/hr) [4] 41.2 115.7 275.2 302.4 36.7 176.5
  ■ Notes [1] [2] [3]
Table 1. Duplicate scanner software performance data on 720 movie files

[1] Czkawka mistakenly found all TV series episodes "identical" because they all begin the same way
[2] Video comparer confused all South Park episodes (there were 16 identical to be found); quite slow despite using Standard mode
[3] this program can only identify identical files, so it isn't a contender in this review
[4] throughput combination metric favors engines that find the most duplicates in the shortest space of time


bar chart with the best performing duplicate film search programs

As you can see from these results, when heavy computational algorithms execute, what matters isn't how the computer program looks but how efficiently it performs. We are not shopping for oil paintings to hang on the wall, but for heavy duty tools.

There is no clear cut winner that excels in every department. Duplicate media finder [DMF] found a few more duplicates (one extra pair of movies) but it did so taking three times longer (slower) than i-DeClone [IDE]. Duplicate Video Search [DVS] was the fastest to finish the scan of the test movie collection, but found 20% fewer duplicate films — and did 4 mistakes, whereas both [DMF] and [IDE] were 100% accurate (0 errors). Which one would you pick?


Best overall duplicate movie scanner and cleaner

🏆 i-DeClone by Zabkat LTD


So the title for the best duplicate video tool goes to the in-house product i-DeClone, how predictable!? But wait, this is not a marketing scam, this acclaim is backed by reproducible evidence. i-DeClone has the highest throughput meaning it finds the most duplicate movies per hour (302.4), and also managed to find 31 duplicate films, only second to [DMF] which as we've seen is much slower and not very good managing duplicate file results. i-DeClone is very capable with previewing, validating and ultimately getting rid of the duplicates discovered. And unlike other specialized tools in this review, it deals with all types of media and documents, not just video.

Please download the free trial and see for yourself, it works full throttle and it will let you remove up to 100 duplicates free of charge. Thank you!

Try it out for yourself!   


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