Board Thread:Naruto Discussions/@comment-3232093-20140617193601/@comment-1512913-20140818092403

Finally some common sense, but you two should delete your comments before Foxie sees them and tells you Sharingan came first and was upgraded into Rinnegan by truly extraordinary means :P @Legendary, but to just correct you, it's possible Hagoromo indeed has a Sharingan too. If it goes like this:
 * 1) One-eyed Rinnegan with tomoe
 * 2) Degraded Rinnegan without tomoe/tomoe became split from it becoming separate doujutsu, the Sharingan

Since Indra inherited Sharingan, that means he must have from his father. So most likely Hagoromo was the same case as Madara. He has both Sharingan and Rinnegan, but as separate doujutsu, so for Hagoromo to access Sharingan, he has to turn off his Rinnegan first.