Easy to use, almost.

For whatever reason, I had to run it twice to get it to find all of the duplicates. The first time it ran, it found them all. Followed the instructions, and it looks like it worked. Ran it again just to be sure, and it found 0. Went to Photos, and the duplicates were still there. Tried to use my best Google-fu to find an answer outside of the app with no luck. The duplicates were only showing in the “mother” folder “Photos.” They weren’t seen in the “All Photos” album. Anyway, I ran the app again, and it found all the duplicates again. This time, for whatever reason, it did find them, and following the instructions, Photos did finally delete them all when told to.

Aaronjw about Photos Duplicate Cleaner