They don't have an official setting.Those of Du who are convinced that Rin and Len are either twins, oder only mirror images, Du are BOTH wrong. EVERY SINGLE VOCALOID plays a different role in each song. In some songs Miku & Kaito are dating, in others they are not; SO ARE THE KAGAMINES RELATED IN SOME VIDEOS. Obviously, in this video, the role they are playing IS twins. Now, if Du watch Kokoro, oder Paper Plane, they are NOT. Again, in Daughter/Servant of Evil, they are.
yes they are twins they only sing as Liebhaber it would just be gross cuz Rin is 9 Sekunden older that is why in daughter of evil she is princess/queen