How do I detect when two CharacterControllers collide?

I have a multiplayer game where player one moves with WASD and player two moves with the arrow keys.

I move the CharacterControllers with CharacterController.Move, and movement works great, also colliding with anything else (SphereCollider, BoxCollider etc) works great with the CharacterController and is detected in OnControllerColliderHit.

The problem is when both the CharacterControllers collide: It isn't detected by anything. not Trigger, Collision or Hit. How do I check if the players (CharacterControllers) collide?

I guess it's something about the fact that both objects technically are kinematic and I'm supposed to handle it myself? How should i handle it?