Hi all,
I have a USB Xinotech dual as main controller, for joysticks and buttons 2 players and it works well for many cores.
And to use as well as original device, I have place 2 USB ports to plug USB specific controllers (like N64, GameCube, or PlayStation controller, which need many controls). Independantly, they works fine but i need to unplug xinotech controller, plug the new controller and restart retroarch to use it without problem. In other case, the xinotech stay as main controller and the “new” USB controller doesn’t responds in game (nor in menu…).
So, i think about a udev rules for the USB controller that detect plug automatically, disable xinotech and restart retroarch. And when disconnecting, reactivate xinotech and restart retroarch.
If someone has another way to make them working at the same time, it will be good too 
Thanks by advance for your replies 