Can't sync: same pocket pc, second desktop, same database on the server

There may be an obvious explanation for this problem, but I haven't
discovered it yet.

I need to sync with an Access database located on a server using an iPAQ
pocket pc. When I set up a partnership with a desktop computer, it always
syncs as expected.

What I haven't been able to do is set up a partnership with a second desktop
computer using the same pocket pc that will sync with the same database
located on the same server. In other words, I need to be able to update
Access database records on the pocket pc and then sync it with either of two
desktops that it is in partnership with. I get an error and am denied
access to the database when attempting to sync from the second desktop.

I'm not sure that it's relevant, but the iPAQ runs Win 2003, the first
desktop runs Win 2000, and the second runs Win XP pro. I use the current
Activesync 3.7.1 and a third party database program called Data On The Run
to interface with Access 2000.

It this just something that can't be done, or is there a way to accomplish
it?

Thanks.