IME the faster grower wins. my polyps grew till everything else was shaded and died. then the polyps stopped at the edges, grew larger and chunks came off that seeded the rest of the tank.
reminds me of the dogs in hurricane katrina. all the initial survivors made it to pieces of dry land; lots of animals, people, etc. rescuers only had room for people on their boats. the next few days only dogs were left, they ate everything else. a week later only big dogs breeds remained- they ate all the small ones. a month later only 1-2 pit bulls remained per island...