Technically, you don't need a special module for player vs player. Almost any module can do. You just have the different player groups be competition to each other in the race to win the McGuffin, rescue the princess, kill the dragon, or whatever the purpose of the module is.
That said, Dungeon mag had a few adventures called The Champion's Games (I think that is what they were called). There was a Champion's Games I & II.
The premise of the modules was a competition between teams to solve a series of challenges with the winning team being the one who gained the most points. However, the teams don't actually face off with each other (each team faces the challenges as a independent team, so it is not a free for all).