Were not the primenode rates changed in which the primenode 10 and 20's also got 100%?
Were the keys changed with the stake rate change or was it just a change to the stake rate associated with each key?
New keys were
not issued, it was a change in the stake rate associated with the keys
https://github.com/PaycoinFoundation/paycoin/commit/cf1eaf6a485281a9150e0b21e6232c0830d8697bShouldn't there be built in protection to prevent more than one wallet from staking with the same prime key?
Yes, it's called decentralization, having the same stake rate for everyone.