Well, using the duplicate row feature in Sheets should be possible, but sadly it works the wrong way.
We don't want to remove the duplicates from the file, we want to surface them.
Of course, there's a workaround for that. 🙂
Keep a copy of the original list, and after you let Sheets remove duplicates, you compare the two lists (VLOOKUP works), and it'll show you which files are dupes.
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https://wheretofind.me/@NoSubstitute