Justin,
I have had both kinds of Dragonets and Scooters together in my large tank, but I have a lot of hiding places. They would chase each other occasionally, but the Spotted and Mandrian dragonet were the ones that would spar. They never chased the Scooter and vice versa. I recently had both kinds of dragonets in my 32gal tank and the Spotted dragonet beat the heck out of the Mandarin one, so much so, it almost killed it. I had to remove it and put it in the larger tank. My only problem in the larger tank is with dragonets jumping out. They're one of my favorite fish so it's a bummer to find them dried up on the floor.