I’ve been trying to configure two controllers to work correctly within snes9x for the better part of the afternoon.
What’s happening is 1P’s controls are all sorts of wonky, Select closes the emulator, A resets the game…
2P is better, but still isn’t totally functional.
I’m using two of the “Classic USB Super Nintendo Controllers” you get off Amazon and such. G-Tron brand, and all grey/purple.
I’ve run the controller config through RetroPie-Setup, and tried to map it through snes9x as well.
Two player works flawlessly on NES, and my controller works well on GBA/GameGear emulations.
To me it sounds as if you have mapped the modifier button incorrectly. You can define a button (select for example) that when pressed in conjunction with another button will execute emulator functions like exit, reset, savestate handling etc.
What version of SNES9x are you using, the standalone or the libretro core? If you are not sure: Do you use RetroPie from the SD card image and have you updated anything at all?