Rock Band 3 [BLUS30463]

Im having a weird issue. my wife and I were playing with 2 guitars last night and today it is still trying to play 2 player (2 guitars players 1 and 3) even though only 1 is plugged in and turned on. the one guitar is controlling both players at the same time. i dont know how to get it to go back to one player.

sometimes when the controller is unplugged it doesn't remove the player, it just set's them both to use the only available device.
To fix it, go into the gamepad settings in RPCS3 and set the player 3 handler to NULL.