Having tried nearly all the commercial duplicate killers, I wasn't expecting much from this freeware offering. I was therefore very surprised when it performed much better than the commercial apps I'd tried. Very fast for one thing, even when doing a byte by byte comparison. No issues with Java on my iMac.

The only slightly untoward thing I noticed was that files really are deleted (not sent to the Trash). However, you can choose to move them to another folder if you prefer.

This is much too good to be free.