I saw one episode of a dubbed anime. It had twin boys who are not really human. They look human, but they don't age as fast as other people. The twins are in an space ship with some normal humans. I think they were going to a new planet or something. Well the twins got along with a older girl, but everyone but the twins die by the end of the first episode. Oh, and one of the twins was like an evil twin. When the good twin got his haircut by the one chick, the evil twin cut his own hair to differentiate himself, i think. If you know the title, please tell me.