I found this in the backup.conf:

emulationstation.pad0=03000000790000000600000010010000:DragonRise Inc. Generic USB Joystick

emulationstation.pad1=03000000790000000600000010010000:DragonRise Inc. Generic USB Joystick

Looks like recalbox gives both the same id. Maybe thats the problem. But how to change that?