A good quality duplicate file finder?

I tend to deal with a large number of people who are semi-computer literate, and I’m seeing an increasing number of them do things like make a mis-click and drag and end up with two copies of their documents folders, one nested within the other. Of course, they don’t realise they’ve done this, and go on using things, sometimes saving to one folder, sometimes to the other, until all is chaos. We also have students making ‘backup copies’ of stock video clips provided for them to practice editing with, which they then save to the same fileserver, resulting in multiple copies of very large files.

What I need is a recommendation for a good utility that will find and help eliminate duplicate files between two distinct folders, or within a single one, as well as showing similar files that may be different versions of the same initial file.

As this is a relatively simple concept, there are approximately 50 shareware authors out there who have created their own implementation of this, and I assume that most of them are rather ordinary. So, what do you use?

Personally I never tried this one (no need yet for a tool like this) but I think somebody here recommended this site in one of the utilities threads, and I kind of like this site.

This sort of situation is exactly why I fervently wish there was a Windows policy for disabling drag-and-drop file operations. Unfortunately, as far as I’m aware, there is not.

No idea if it’s ideal for your purposes, but I use Clonespy.