Different PIN on different devices?

I am switching between a Q10 and a Nexus 4 and they both have different PINs.

Is this a common thing? I thought since BBM uses BBID, the PIN is always the same? I really prefer having one PIN, is this just me or is everyone else using multiple devices experiencing the same thing?

I think a PIN is a per-device thing.

If someone has multiple BBIDs and one Android/iOS device with BBM on it, it would be interesting to see what happens if both BBIDs log in on the same phone.