USED PCM for backup programming

I'm trying to get everything sorted out before my HPt equipment arrives. I have an 08 Cadillac CTS. I purchased a used PCM from a similar vehicle. The used PCM also has the same 4 letter code on the case, as well as part number and is the correct PCM for the car.

Am I correct in thinking it only needs to be VIN matched, or is the process a lot more involved than that?

I don't want to modify the tune, just create a backup stock PCM.

Thanks for all the help :-).
The used PCM needs to be programmed per the VIN.
HPtuners can not access all of the modules, apparently 7 & 8 are beyond its reach if my info is correct in which case it is probably not the best resource in this application.
Once the PCM is flashed, pass/key relearn is necessary. You can not switch between PCMs without performing the pass/key procedure.