Board Thread:Personal Help, Advice and Support/@comment-1659166-20141101200215/@comment-24770490-20141101200822

They have different names, it's that simple and the names have an important part in the episode too.

Mad Ben is not Mad Ben in the actual show, since he didn't necessary know there are other Bens. He is just Warlord Ben Tennyson, so he doesn't call his transformations Mad (alien name).