The debian mirrors are in a DNS round robin...if you're using
http.us.debian.org it's possible one box got updates from a server
that had been synced, and the other box from a server that hasn't
finished syncing.

-- 
Andrew S. Zbikowski | http://andy.zibnet.us
 A password is like your underwear; Change it
 frequently, don't share it with others, and
     don't ask to borrow someone else's.