My roomates and a friend of mine have been getting a lot of DUP errors
   when writing a large number of files and then rebooting.

Well, you've supplied *VERY* little information.

What kind of machine (CPU, etc.)?  How much memory?  How are the disks
partitioned?  Old or new format file systems?  What *is* the phase of
the moon, anyway?

I certainly haven't seen a problem like you described, on numerous
machines.