ok so im watching one piece for the first time and am currently on episode 100 but a few episodes back when they landed on the snowy island where they picked up the reindeer doctor. I was under the understanding that only one person could utilize a devil fruits power at the same time, but the old kings guard and reindeer seemed to have the same ability and that is animal shape shifting they both have three forms. was the doctor originally a reindeer then ate the fruit or was he a human first? idk if I walked away from the computer when they explained it but to me it seemed they ate the same fruit. any insight on this or did they eat different fruits that are just similar in ability. and if anyone has like a list or chart of all devil fruits id appreciate it