Way to look for duplicate files across two hard drives?

EvilYoda

Lifer
Apr 1, 2001
21,198
9
81
So I started with 4 hard drives, 2x 500GB and 2x 1TB, all filled with old data that was saved from prior installations or whatever. It's down to the two 1TB drives and I thought I'd have more duplicates but at first glance I can't see much.

Is there some software I can use that will help me compare the two drives? The plan is to turn the old computer into a media server running two 2TB drives in RAID so I'll have to sit down and move this data over one way or another, but I was hoping that I wouldn't have to worry about the same file in two different places.

Long writeup for a short question, sorry. Thanks if you can help!