Why can't I delete bulk duplicate photos from my Mac and iphone

Photos is checking for duplicates, when you import photos. So there should not be duplicate photos in your Photos library. That is probably wh Apple omitted a tool to screen the library for duplicates.

You could use third pary tools to search for duplicates however. These applications are compatible with Photos:

• Powerphotos: Fat Cat Software
• Duplicate Annihilator: Brattoo Propaganda Software - Products
• PhotoSweeper: http://overmacs.com/photosweeper.html

If you have duplicates of a different pixel size in your library as well, then consider Photo Sweeper. It can compare the photos based on histograms or bitmaps, so you can detect edited duplicates as well. Also, you can set up rules, which photos to keep and which to discard, for example give preferences to the newer photos, the photos with the larger pixel size, or the photos with metadata assigned.

PowerPhotos is a great tool to have, when working in Photos for browsing several Photos libraries at once and for seeing photos annotated with metadata. It can move photos between libraries and help you to merge libraries. But the duplicate detection is not as versatile as in Photo Sweeper. It can mainly detect exact duplicates.

I don't know much about Duplicate Annihilator, so I cannot say how it will compare to the other two.

depending on your undisclosed setup it may be automatic, may require an iTunes sync or may be a question for the iPad and iPhone forum

LN

Once I delete duplicates on my Mac do I need to delete duplicates on my iPhone and iPad? If so what app should I use.

It will depend on how the photos are synced to your mobile devices.

• If you are using iCloud Photo Library on all your devices, the deletion will sync to your other devices. iCloud Photo Library FAQ
• If you are syncing the mobile devices with iTunes Photo Sync, just sync again to remove the photos that are no longer on your Mac. (Sync photos to your iPhone, iPad, and iPod touch in iTunes - Apple Support)