How do I Sync 2 diff Palms on same PC?

A friend of mine just told me he never backs-up his Palm Zire m150 because his wife backs her Palm up on their one-and-only home PC. He says that WinXP doesn’t like his Palm because hers is defined.

Not knowing anything about Palm Sync-ing (never owned one), I suggested he try Sync-ing hers up from her XP Userid and try Sync-ing his up from his XP Userid. He said he tried that and it didn’t work.

Any suggestions that I can pass along to him?