Kasz216 on 09 May 2008
I think I do. Missions are single player. When you play them as two players the first player plays as the Marvel hero. While the Second Player gets to play as the villians.
So to get the unlockables you need the 2nd player to quit out of the game until you finish the mission.
I'm about 80% sure that's what is happening to you but i haven't played that game in a year.
