I am running V4.0.5. No matter what I do when I add a motion sensor to a scene the motion detector is add as a responder to the scene. When there are two motion detectors in the scene each both sensors are responders to the scene therefore, when the scene is activated by one of the sensors the other sensor is expected to respond but it is sleeping. My solution for now is to have two scenes for the lights, each one having one of the sensors.