I dont know why blizz cant allow us to use the same authenticator code 5 times on 1 bnet account. If someone is that desperate to hack my account that they will install keyloggers and a monitor for the authenticator code then Id rather they hack the account than have all this unnecessary security in place. After all im going to get the accounts back in a few days anyway (Quite often with a ton of gold and items that I didnt have before).
I have heard of people getting hacked, using an authenticator, when it was the old way so they shortened the time a code is good