Why Didn't It Find My Duplicates? What Counts as a Duplicate or a Similar Photo

The problem

You know your library is full of the same pictures, and the scan says you’re clean. Or it found 12 photos and you expected 2,000.

That isn’t a bug, it’s a choice about what to call a duplicate.

The two definitions

Exact duplicate. Same pixel size, same file size and the same SHA-256 fingerprint. Byte-identical. Safe to delete one.

Similar. Photos taken within about 10 seconds of each other whose small visual fingerprints are very close. Built for burst shots and retakes.

Screenshots are found by iOS’s screenshot flag.

What falls between

• The same picture saved twice from a chat app. Chat apps often re-compress, so the files differ.
• Edited or cropped versions of a photo.
• Similar scenes on different days.
• Two photos of the same thing taken a minute apart. Outside the 10-second window.

None of these are grouped, because grouping them risks deleting photos you wanted.

What to do about those

• Use Largest First in swipe mode and review the biggest items in your library.
• Check your Photos app’s own Duplicates album.
• For chat-saved images, look through the albums those apps create.
• Rescan after you clean; the app tells you when the library has changed.

The tradeoff

A stricter definition means fewer finds but almost no wrong ones. In a tool that deletes photos, that’s the right side to err on.

FAQ

Why did the scan say “All clean” when I know I have duplicates? Because it only counts identical files and near-identical shots taken seconds apart. Re-compressed, resized or edited copies don’t match.

Can I make it more sensitive? No, the thresholds are fixed. The strictness is to avoid deleting real photos.

What should I do instead? Sort by largest first and review the biggest items, and handle chat-saved copies by hand.