Just a quick heads-up here. I’ve now read on four separate sites that some people are ordering more than one Blizzard Authenticator for themselves, eg. if they play on a desktop computer and a laptop.
It doesn’t work that way, I’m afraid. You can use one single Authenticator for several accounts, but not the other way around. Multiboxing? One authenticator for all your boxes is enough. WoW, Scarcraft2 on battle.net and the future diablo 3 accounts can all be protected with the same Authenticator. But you can’t have two authenticators protect the same account twice.
From the Authenticator FAQ:
Can I apply my Blizzard Authenticator to more than one account?
Yes! You’re welcome to associate a single Blizzard Authenticator to as many accounts as you like. Please remember that you must have that Authenticator with you to log in to any of these accounts afterwards.
Can I keep one Blizzard Authenticator at home and another at work, and have both associated to the same account?
No. Each account can have only one Blizzard Authenticator linked to it at a time, so you would need to carry the Authenticator with you to log in from different computers.
Hope that clarifies it.