Duplicate File Finder by Nektony - Duplicate File Finder is a Free app to find and remove duplicates on your Mac.
Double Commander - Double Commander is a cross-platform open source file manager with two panels side by side.
dupeGuru - dupeGuru is a tool for finding duplicate files on your computer.
Total Commander - A Shareware file manager for Windows® 95/98/ME/NT/2000/XP/Vista/7, and Windows® 3.1.
MacPaw Gemini 2 - The intelligent duplicate file finder
XYplorer - File Manager for Windows