Deduplicating photos

I have thousands of photos on my Windows 10 machine. Many are duplicates -- or multiple versions of the same photo that have been cropped, retouched, etc.

I'm looking for software that will help me weed out the identical duplicates, and make it easy for me to choose the best of a group of retouched versions of the same photo (or keep them all but rename them so it's clear they're all related).

(Bonus points if you have a good idea how to manage that process without having to export everything from Picasa first.)

Thanks!

You can't go by frame numbers, because they roll over after 10K shots (over 90% of mine would show as duplicates). Nor can you go by user names, because humans aren't creative enough to avoid duplications.

The best solution I've found is to keep derivative photos in subdirectories, along with the originals and mastered images. The master directories are named with a date code and brief description. I group related photos from different directories into Lightroom Collections. Collections are by reference, not physical copies, hence take very little space, and are easily traced to their original folder.

If you don't maintain images in locations of your choosing, independent of a piece of software, now is as good a time as any to begin..

Don't have W 10, just 7, but if you go to Windows Explorer, View, Details, Choose Details, you can select a variety of date (and many other) measures, sort by those in a variety of ways, and using those factors Delete selections, save to folders, archive, whatever. A variety of other details allows parsing the data / images any way you choose.