User blog comment:Tomj8937/Who are the 2 lost primarch's:/@comment-1932673-20100826185853

Thats total rubbish, Omegon and Alpharius are genetically identical, plus in the horus heresy series horus has a warp-induced dream/vision where he goes back in time and touches the capsule of the unknown primarch (not 2) and feels "untapped glories within". Therefore Omegon cannot be a lost primarch and old army books/codexes and rule books should be treated with caution as GW changed or deleted a bunch of fluff, for instance the Squats.