Board Thread:Warhammer 40k General Discussion/@comment-67.197.44.118-20130216115719/@comment-7186329-20130424181656

Yes, they have used substitutes to fool other Space Marines and the imperium, which have had no previous contact with the primarch twins, fooling Guilliman about his brother is simply not possible.

The Astartes of the Alpha Legion may be tall and go throught surgery, but that is not nearly enought to decieve a primarch. Also comparing an Astartes to a Primarch is like comparing a chihuahua to a dragon.

Roboute could have used a needle to take some DNA, then burn the corpse.

One of those twins is dead, and I would go as far as to say it was also `part of the plan` of the Alpha legion. If those brothers shared a single `soul`, then one on the other side, the Warp, could protect the other half.