****** (site that rhymes with "edit") theory on Eyepatch Morty: He is the Rick C-137's original Morty (which is why he created that elaborate ruse just to get C-137 to his hideout without anyone knowing about it). This is derived from several observations from that episode:
--When controlled Rick is going through our Rick's memories, we see an image of Rick holding a baby Morty. However, Rick has only been back with the family for a year after being gone for 20, and his Morty is only 14; which means he didn't know Morty as a child. Rick's absence is brought up in the episode (first line).
--There is a voucher for replacement Morty's.
--Rick talks about a Morty getting cocky being a bad thing; the scene then immediately cuts to Eyepatch Morty joining the other Rick-less Morty's.
Not well supported with direct evidence, but I like this theory. I think an 'evil' Morty can turn into a great villain for season 2.