Yes, you could possibly get away with it. You could tell them that you accidentally wiped the device and need a new activation password. then just activate the new BB.
As an BES Admin, I have to tell you not to do that. If they keep inventory of the PIN's, they will know you switched it. If it is a corporate device and not a personal one, I really recommend you not do that because you could be fired. Good luck and sorry to hear about the windows mobile thing.