'Goblin' is the original name given to them by Ralph Davis when he had unproven/out of Africa snakes that looked like they may have something going on. They were later proven to be the same thing as the yellow bellies. Ralph still calls 'his line of yellow belly' goblins. It's like yellow belly is the generic name, 'Goblin' is the specific line. It's just like the phantom/mystics. If the line came from Ralph, they're phantoms but if the line originated with Anthony McCain in IA, they're called Mystics. It's still the same mutation, it's just a way of differentiating the lines.