I redeemed two events in Mystery Gift. Redeemed the first one (Birthday Pikachu), tried redeeming the second (Birthday Eevee) but it said I could only redeem one per save. Backed up my save on PKHeX, and reloaded the same save file, one where I didn't use the code to get Pikachu. Redeemed Eevee, and backed up the save.
They both have the same PID. Different EC, different IVs, different Height/Weight stats. So I'm wondering, when is the PID determined? Is the PID pre-determined based on the