As long as both DMS' have the same firmware and that matches the box it will be fine.
Actually, that doesn't really matter. The firmware that talks to the car head unit will only be updated if the "forceupdate" flag is set. On a regular DMS, that won't happen unless you use one of the DMS managers to put new firmware on the DMS.
All of the other files are backward compatible - just use whichever head unit version is newer. Normally, this doesn't matter either, but sometimes a newer firmware won't work properly with older system/player/daemon files.
You can probably ignore everything I said above and successfully swap DMS cartridges between different car types without any problem - I just figured I'd post the technical details in case anyone was interested.