Q : Can I use my old PIN after requesting a new PIN? A (By Google) : Yes. All replacement PINs issued for your account will be exact duplicates of the original, so you can enter any of the PINs that you receive, regardless of which one arrives first.
No I dont think your PIN is the same the second time. They told me to wait abit longer before requesting a new PIN because the old one will become useless.
Maybe not same but as G said all of them will be work with your account Take a look here https://www.google.com/support/adse...=20917&ctx=en:search&query=pin&topic=0&type=f