There is one way around all of this. Create multiple battle.net accounts. I've confirmed the same authenticator attached to multiple battle.net accounts allows the same code to be used at the same time. So if you have 5 WoW accounts for example, instead of creating just one battle.net account and merging all of those to the one battle.net, create 5 battle.net accounts. Merge each WoW account to each battle.net account and the authenticator that was attached to each WoW account will automatically be attached to each battle.net account. When Keyclone, Octopus or whatever you use to start WoW up with, you enter the account name with the separate battle.net account logins. The issue of having the same authenticator code used at the same time goes away because you have separate battle.net accounts. I've confirmed this. However, Blizzard could possibly change this is in the future but for now it works by logging in at the same time without any issues.