Call of Duty delux - CD key problem

Hello,
I have the Deluxe edition of Call of Duty (COD) and entered the wrong key when I installed the game. I can play the single player version but when I try multilayer I get the message "CD key is in use, please try again later".
On the box there are two key numbers one for COD and one for united offensive (UO) and I entered the wrong one when installed COD.
I use a Mac OSX
Help any one?
Thank you