Dedupo 1.6

Easily find and delete duplicate files on your Mac. You can customize the search location, criteria and scope.

After search, you can use auto-marking to automatically mark duplicate files for deletion to trash. Currently it has auto mark by date modified, file name length and folder.
Dedupo uses byte to byte comparison to find duplicate files so the duplicates have 100% identical content (file's copies). It also has thumbnail preview feature, you can instantly get an idea what those files are.
You can download free trial on http://www.dedupo.com