So I noticed that there is a bug in the game where it actually allows you to play keyboard and mouse with controller as a second player on the local machine (even on the multiplayer game). If you have the controller unplugged and join the game (in the map) then plug in the controller, it opens up for a second player. You can move but not use the inventory since the other player is locked for the supposed split screen that never happens. Instead it locks into the same screen for the first player (keyboard and mouse).
on a technical stand of point I think you just need another instance of a layout (for the type of controller), easier said than done but it can work..
