Yes. Tebow was cleared to play against LSU after he suffered a concussion two weeks beforehand while playing Kentucky.
If you are playing a multiplayer game, then yes, you can play two players, or more if you want
You cannot play two players in a single player mode but you can play two players in an exhibition match.
You can play two players on halo 3 with two controllers
Chad Jones of LSU 2007 Football & 2009 Baseball
Currently, up to two players can play Kinect simultaneously
you can play spec ops two players split screen two to four players or online two to eighteen players
Xbox players are unable to play online with PlayStation players because they online play is run through two different domains.