I had a suspicion my video library was full of duplicates. Wedding footage, vacation clips, family videos — saved multiple times in different formats and resolutions over the years.
So I ran my 200 GB video folder through three different duplicate finders. The results were... eye-opening.
Test folder: 200 GB of personal video files
Tools tested:
Tool A found 3 duplicates — all perfect copies with identical file sizes. Tool B found 8 — the same 3 plus 5 more with identical data but different filenames.
Dup found 47.
Tools A and B compare raw file data. If two files aren't identical down to the last byte, they say "not a duplicate." But most real-world duplicates aren't identical files.
They're the same content saved differently:
Same video, different quality. I had a wedding video saved as a 4K file (2.1 GB) and a 1080p version I'd exported for sharing (340 MB). Same wedding. Same footage. Other tools: "Not a duplicate."
Same video, multiple versions. A vacation video existed at 4K (original), 1080p (shared with family), and 720p (uploaded to social media). Three files, same video. Other tools found zero matches.
Same video, different format. Videos converted from MOV to MP4. Same content, different file type. Other tools: "Not a duplicate."
Same video, renamed. vacation_4k.mp4 and beach_edit.mp4 — same footage, different filename.
Instead of comparing raw file data, Dup compares what the video actually looks like.
It samples frames throughout the video, creates a visual fingerprint, and then compares fingerprints across all your files. Two videos that show the same footage match — regardless of resolution, format, filename, or file size.
So vacation_4k.mp4 (2.1 GB) and beach_edit.mp4 (340 MB) show ~94%
visual similarity. Dup groups them as duplicates.
Does it take longer? Yes — a few extra minutes because Dup actually looks at the video content, not just the file header. But finding 47 duplicates vs. 3 is well worth the wait.
1.2 GB of duplicates
3 files found
38 GB of duplicates
47 files found
I was wasting 38 GB on duplicate videos and didn't know it — because every tool I'd tried before told me I only had 1.2 GB of duplicates.
After seeing the video results, I ran my Photos Library (85,000 images). Tool A found 120 duplicate photos. Dup found 2,847.
The difference? Hundreds of HEIC and JPG pairs — the same photo in two formats. iPhone originals and their shared copies. Screenshots taken twice. Photos imported from multiple backups.
Total space recovered from photos: 12 GB.
50 GB freed
Combined photos + videos — all from duplicates hiding in plain sight
If you've ever wondered why your Mac's storage keeps filling up despite having "not that many files" — this is probably why. You have duplicates hiding in plain sight because your tools can't see them.
Most apps are great at finding exact copies. But most real duplicates aren't exact. They're the same photo or video saved in a different format, at a different size, with a different name.
Dup sees through all of that.
Dup is free on the Mac App Store. Scan any folder and see what your current tools are missing.
Find the duplicates your current tools miss
Dup finds similar photos and videos — not just exact copies. Free on the Mac App Store.