Does each AU get 2 visits free, or does the entire account get 2 visits a year?
You can get Lounge Club cards for any AU on the account (and even others who are not on the account). There is another thread where this was discussed...
Just follow the same link and procedure you use for the first one, and repeat for as many cards as you need (but remember, whatever CC you put in will be charged for any visits past the first two in a calendar year).