Duplicate Files

[OldFellar]

I am confused as to which files to delete. I have found NO information about the subject that answers my problem, which is this. If I have a lot of duplicate file to delete, should I delete ALL but one of each group of duplicate files or do I need to keep 1 of them each for each
 program that uses the particular file.Will a program find its file, where ever it is, or is it possible for 2 programs to use the 1 file at the same time.If not, how will I know which program needs a copy of the file saving?

[Allan]

Why delete any?

[OldFellar]

Do they not take up room and slow the PC down a tad? It seems a handful of folk have written programs to do just that ( clear up duplicate files in order to speed up the PC ).

[Allan]

Unless your hard drive is small or very low on space, duplicate files neither slow down anything nor need to be deleted.

[patio]

And to add to Allans comments ...removing them generally will cause havoc...

[Broni]

Especially since Vista and 7 (not so in XP) keep a plenty of system file backups in several different locations.
Very handy, when some system file(s) get corrupted.

[BC_Programmer]

Additionally, some "duplicates" aren't duplicates at all, but hard-links to the same files; this is especially true with the various junctions/folder hard-links in later windows versions.