Board Thread:General Discussion/@comment-110.136.195.9-20130720172618/@comment-5051846-20140219205555

Yeah, they're not canonly twins, or anything. XD It's up to the producers to decide. So you'll see some songs with them as related, some songs with them as lovers, some songs with them as clones...

All these are legitemate, and may be played at the same concert. That is the nature of many Vocaloids. Within the universe the producer creates, their song is canon; but there are many different universes.