It's possible to sync two devices to Outlook using Chapura's Pocket Mirror Pro and using one Outlook file.
This may not be your preference but it's possible.
I use a 650 and T5 on the same PC with the above configuration so that both devices are syncing to the same Outlook user for Calendar, Tasks, Contacts, and memos.
But you still have to have two different Palm user names, one for each device of course.