thumbnails as a measurement
Oh, so you're saying take (some arbitrary, some set time into the video, say at the 1.sec mark or whatever) "thumbnail" shot of the video & compare the thumbnails (rather then audio length, which is the current situation).
(And do note, that for "ms" diffs, & other reasons, that thumbnail may not necessarily be "identical"...)
(I'll note that from other softwares that work in a similar manner, results will vary...)
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If you wanted to search, based on Length, with say a 1 sec time variance, you can do that with
Everything 1.5 Alpha.
(By default, Everything takes ms into account, but you can change that.)
You would add a (Property), Length: column - indexed or not (depending on your needs).
(If not indexed, it uses a lazy-load, so only when the column is brought into focus, does it load the Length data.)
Then right-click the Length column header, Find Length Duplicates.
That would
find duplicated Length videos.
You can then drag said videos into your player (
mpv.net media player, a mpv front-end, works very well for that, retaining the sort order as listed in Everything), & use mpv.net to "preview" your clips...
Actually, Everything itself can also display video thumbnails, so that in & of itself may help you.
(Set the View, to Thumbnails.)
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(I've never actually used AllDup 'Find video & audio files on the basis of the audio length' nor Everything's Thumbnails.)
And depending... on any number of factors, one tools, or combinations of tools, might or might not work "better" for particular data sets.