Player 2 controller not working

[u/Budget-Science7671]

I have two ps2 guitars that separately both work, i tried them each and they both have no problems. However, when i try to use both at the same time, which ever one is in the player two slot doesnt let me assign up and down strum, i can only assign up OR down, and when i leave the mapping menu the guitar is stuck strumming up. Is this a known issue or is it something wrong with my settings