I have a backup from a Vodavi XTS MPB1. The MPB1 is going bad. Can I upload that programming into an MPB2 that is running the same software level?

I would use Windba a convert it so your flex codes don't get screwed up.

By this, I assume you mean, open the DBA and create an MPB2 DBA, then choose to download my backup into the MPB2 DBA. After the error correcting, then upload the programming from the DBA to the new MPB2 processor.

Sounds good to me. You don't have anything to lose. Especially if you have a bench test KSU. But most of the MPB failures are simply due to an old memory support battery that needs replacement.