Although, I also thought that Luke would be born from one mother and, Leia another mother(mabye close friend of the queen). So Ben would only be at Luke's birth. Twin could be Star Wars talk for same father. Anakin would take Vader's name in II. Then III would focus on trying to fight against the Empire and, Vader. Then the hiding would happen in III. I don't know something like that. However, I don't see much of a problem of Obiwan lieing where Anakin was. Especially if he thinks that everything else he's saying is the truth(the pilot thing, Vader killing Anakin, ect.). Plus they're in hiding so yeah. I haven't ever read the novels so I didn't know about that line in there. Basically, the way I thought of it Yoda would be the one who knew about the twin thing and, Anakin/Vader thing until Empire. Where he would tell Ben after the "There is another" line. How Yoda knew I didn't really think about.
