If you have one user name on the server, all mail from any domain addressed to that user will come to that mailbox. For example:
Username=jarthurs
First name= jerry
Last name = arthurs
Pseudos= jerry.arthurs, jerry_arthurs, etc.
Domains= workdomain.com, personaldomain.com
All mail addressed as jarthurs@workdomain.com, or jarthurs@personaldomain.com or any of the Pseudos will go to the jarthurs mailbox.
One possible workaround:
setup a new user=jerry
you can now use firstname@personaldomain.com and it will come to the jerry account. You would then check the jerry account on your personal machine and the jarthurs account on your work machine.
(you will need to make sure that all your personal contacts us jerry@personaldomain.com and all work contacts us jerry.arthurs or jarthurs@workdomain.com)