I can confirm that the pairing is lost sometimes (7.0.1 on RPi4, 2 x SN30 Pro in dinput/Android mode), but for me it does not depend on the number of controllers that I use. That is, I can pair both controllers, restart Recalbox and they will still be paired.
What I noticed is that I have to turn off the controller when restarting Recalbox. Otherwise it won't connect, even though I'm back in ES and the controller LEDs are blinking (indicating that it's still trying to connect). When turning off the controller and then turn it on again, it connects instantly. I think this is rather an issue with the controller.
