Board Thread:Warhammer 40k General Discussion/@comment-14745711-20140911102114

I am horribly confused about the primarch/s of the Alpha legion Alpharius Omegon. Is he two people or one person? I know I have heard that he Omegon is Alpharius's twin brother, but in the article it often refers to only one person that being Alpharius, as if Omegon is just a last name. So is he two people or one? 