Im very sure the code can be used for 2 tickets for one show and 2 for another. Ticketmaster cant tell where you have used it, but they will no when 4 tickets have been bought.
Im not happy because I bought 4 albums and only got 2 codes. Wasnt sure how many tickets we would get per order. I m at least going to use 8 with no problem. I know I have the 2 local shows so far and maybe more.