when I bought my WJ the salesperson made the booboo of promising me an extra key (only had 1 fob/key). So when I brought it back in for some other work to be done, they had to bite the bullet and give up the new key. They programmed one extra key and fob just fine, but for some reason there was another spare key on the ring. It was cut, just not programmed. I went out and did the program steps and it worked like a charm.
Just a hint though, if you've got an over-excited salesperson you may be able to get an extra key and fob out of the deal