How to show duplicates in my Photos app for cleanup?

Be sure to fully open the Utilities section by clicking on the little arrow

If "Duplicates" isn't there, it's because Photos hasn't yet found any duplicates. Photos has to scan every picture before it can start comparing them, so patience may be necessary.

jimmytoobad wrote:

show duplicates to winnow hundreds of photos

If you want to be more proactive in culling out duplicates you can use of on these two apps.

I've run tests on the these two apps with the following results and found them to be safe to use:

PowerPhotos - ~$30  Free version available with limited functions.

PowerPhotos is the iPhoto Library Manager version for Photos and is very powerful. Although more expensive I would recommend it as it has more capabilities than the others like the capability to merge Photos libraries or copy photos, both original and edited versions, along with their metadata between libraries. You'll need the paid version for duplicate culling.

PhotoSweeper - ~$15 - Demo version available-limited to a fixed number of duplicates.

PhotoSweeper compares bitmaps and/or histograms so it can detect duplicate images even if they have different file sizes, file names, image sizes and capture dates.

PowerPhotos is the top utility app for a Photos library and well worth the price.

If you are using macOS 15.5 as shown in your post, the Duplicates function should be found in the Utilities section of Collections in the left sidebar. Is it absent, empty, or dysfunctional?