Yeah I did wonder about that as well. To be honest I haven't tried that way
The other location its stored as a back up is in C:\WINDOWS\system32\dllcache. Maybe its worth overwriting that one as well.
The whole topic seems a bit voodoo with people talking about doing different things, copying one file, copying lots of files etc.
Of course you could turn off Windows File Protection (its a service), but I don't really recommend that
