Help Please: multiple copies of some exe and dll files in system32 folder

An example is lsass:

lsass(3).exe 13k 8/4/2008 12:56 AM
lsass(2).exe 13k 4/14/2008 5:42 AM
lsas.exe) 13k 8/4/2004 12:56 AM

There are .DLL files with multiple copies as well.

Any help or explanation would be greatly appreciated.

Mike

m.k.b.e.r.k..at..p.a.c.b.e.l.l..n.e.t