Moleskinsoft Clone Remover Free
Full user review
"Good, but limited"
It does as advertised. Finding duplicate files is pretty easy and the interface is functional and mostly intuitive.
It lacks some features that would be good for partial backup cleanup. For example, you cannot limit comparisons to only show files with the same relative path (say, c:\BLAH\xyz.txt matching e:\backups\2008-06\BLAH\xyz.txt, but not c:\test\clone.txt).
If all you want is a software to find cloned documents or duplicated DLLs in a single hard disk, without the need for advanced filtering used in backup management, go with this one. It'll do what you want with minimal effort. Otherwise, you'll have to find another solution.