Yes they can and will wipe out coral. Also be cautioned adding multiple anemones to a tank is generally a bad idea unless they are separated by at least 3-4 feet and do not roam even that could be too close... otherwise you may get to see a real chemical war up close and personal, they may attack one another from opposite sides of the tank shooting nematocysts at the other and anything that happens to be in the path won't stand a chance.