Hopefully, there are some programs that help you finding and eliminating those duplicate files, and by the way, free space.
Duplicate Cleaner is an useful program that will make you say goodbye to duplicate files definitely.
Its interface is very intuitive, and it's really easy to use. Duplicate Cleaner scans your HD and find all duplicate files. you can choose the kind of results the program will throw: size, name, date or even the content. Then, it will feature a list of duplicate file and you'll be able to eliminate all of them in only one click.