I agree a MAC address is meant to be unic but even on 2.2 stock i think i had this too, at least i had MAC address undefined sometimes and needed to reboot so wifi got connected..The MAC Address never has to change, though you do a upgrade (2.3.3) or a downgrade (2.1 or 2.0), the MAC NEVER NEVER change!, this is one bug the beta 2.3.3
In addition, on the 2.3.3 it's the last of my concerns: i'd prefer Gapps working and mac address changing everyday...