I haven’t worked with all of them, but MacPaw’s Gemini 2 is both a photo-duplicate finder and a general file-duplicate finder, so it’s definitely worth checking out. I’d be interested in hearing what other members are using.
I have now tried it, and so far find it very unsatisfactory. It got rid of 3 duplicate photos in my Photos library, and I know there are MANY more. I will try some other app. Thanks for ther suggestiion though Charles.