duplicate files not working in CCleaner Bug Reporting Posted November 14 · Report reply CCleaner can find duplicated files for you, - but you have to select which, if any, you want to remove yourself. CCleaner cannot make that decision for you, only you know which you want to keep and which you want to remove. You would not be happy if CCleaner removed the wrong duplicate. Only ever remove duplicates of your own files, photos/videos/documents/music files/etc. that you have saved. Don't remove any duplicated system files, copies of system files are often needed in more than one location and deleting them may (will) stop your computer working properly.