Apple Photos stores your entire library inside a single .photoslibrary package. Cleaning duplicates safely means using a tool that talks to the Photos API, not one that tears files out of the package.
Short answer: for the Apple Photos library specifically, use Gemini 2 or a similar API-aware cleaner. For the source at import time, use Cleanor on your phone before sync so duplicates never reach the library.
Why you should never open the .photoslibrary package
The file at ~/Pictures/Photos Library.photoslibrary is a database, not a folder. Right-clicking it and manually deleting files inside Masters or Originals corrupts Photos.
When the app next tries to render a thumbnail for a file you removed, it fails. Edits, albums, and iCloud sync break. The only safe path is through Photos itself or through a tool that uses Apple's API.
Gemini 2 for the Photos library
Gemini 2 by MacPaw is the widely recommended option. It:
- finds exact duplicates and visually similar shots (like four angles of the same sunset)
- selects keepers using rules you can override
- deletes through the Photos API so items land in Recently Deleted for 30 days
Nothing is permanently lost until you empty Recently Deleted yourself, which is the right safety net for a lifetime of photos.
Cleanor at the source
If most of the duplicates are coming from your phone's camera roll — bursts, screenshots, near-duplicates — running Cleanor on the phone before sync stops the problem at the source. That keeps the Mac library lean without touching the .photoslibrary at all.
When to pick which
- library is already bloated on the Mac → Gemini 2
- camera roll is the real source → Cleanor on the phone
- drive is small and you also want broader cleanup → use both in sequence
Better next routes
For a broader comparison view, use the best desktop cleaner apps compare page.
For the broader Mac framing, continue with How to Find Large Hidden Files on Mac.