He was labeled as DBTPK. Yes the black is part of his color I love the the way it looks on the edge of his fins. Im assuming he is an older fish or maybe wasnt a good breeder as he is quite large compared to some of the other bettas.
He might be a black butterfly. That's how my red veiltail was. He probably wasn't a good product of a breed due to the fact that he's got an unformed doubletail. It should be centered and all the way to the base of the tail. He could also be older. Most pet store bettas tend to be around a year old. Still, he's gorgeous! :)