Deleting duplicate files can be a good idea, but it won't save you all the time. It is mostly useful when you may have gotten the same file twice, especially music, movies, photos, and large files in general. They should comprise a list of a few duplicates that are really using some unneeded space.
But duplicate cleaners look for files in an entire disk unless you specify otherwise. They will probably not know the difference between a temporary folder you created and the actual folder you use for your files. If you have your duplicate cleaner simply delete every duplicate leaving the "originals", you may be left with the file you want being left only in the folder you don't want.
Other files may be present in more than one program folder, and be equally necessary in all of them. That's why some cleaners, including my suggestion in an above post, excludes Windows and programs folders by default (which does not include program folders you created like C:\Games or C:\My Programs).
If you really need more space, and especially if 1GB will make such a difference for you, it may be better to simply copy some big rarely used files like music and movies, etc, into an external media.
the best is Auslogics Duplicate File Finder
