I know this is way late, but figured I'd throw an answer in there.
You CAN sell it, but whether it's technically illegal, I don't know. I figure that it came with a product that you purchased, and you should be able to sell it if you wish to, especially since you already have the game. Although, I wouldn't sell it for too much. Give someone a good deal.
I bought another PS3 a few years ago after my orginal finally pooped out on me. It came with the Uncharted 1 and 2 Dual pack as part of a deal with Best Buy. I already have those two games, so I decided to sell it. Granted they were physical copies and don't require a license key like a PC game, but I still see it as the same.
I recently purchased a GTX 770 and it came with three games. I may wind up selling one or two of them, as one I already have, and the other I have no interest in playing. May give them away, not sure yet.
And that brings me to my last point. You could be really generous and just give it away. Make someone's day.