4 train operation is unnecessary for the dueling aspect. When a train exists the station, it will meet the train before it that has completed the blue track, and the train before that will be entering the station after completing the green track. Two trains on the tack, one train in the station, and they rotate.
In a perfect world, with perfect people, and perfect ride ops yes it's possible. Hell if it was Cedar Point it'd probably be possible. Let's keep it 100, this is MM we're talking about