Acans will do that; I have one similar to that with two mouths but one polyp. Sometimes the acan with grow new heads and sometimes heads with grow a second mouth and split.
I got this as a 3 polyp frag and all the sudden it started growing single polyps with 3 and 4 mouths. They're all over. Im putting my nephew's Tiffany Acan in my tank to see if it does the same. He's had his for like 4 months and not a single new Polyp has fully developed so it should be interesting to see what happens.