An update by Sorgelig from July 3'rd states:
Can someone please explain how to use this? I am having a hard time getting my head around this. The WIKI seems not updated unless I'm reading it wrong.
I can map all different controllers in Main, and also in the cores, and sometimes I can use multiple of my devices as player one, but sometimes pressing the second controller maps it to player two. It would be awesome to understand the logic behind it.