Don’t bother

Yes it’s easy and yes it found lots of duplicates and let me resolve them, BUT:
It didn’t recognize when I duplicated a photo in the Photos app and cropped/edited/changed it, and so the app tried to deleted it
It only found a small percentage of duplicates, I still had tons that are easy to identify (like the same file name plus a ‘-1’)

And yes I tried to run it multiple times hoping each time it would catch more and more duplicates but after one pass it couldn’t find anything else.
Maybe this is why they try to get you to upgragde to the paid version as soon as you launch the app...

ctoes about Photos Duplicate Cleaner, v1.7