Spoilers:
You mean Evil Morty? I got really suspicious of him when he gave that great speech, and I was almost certain that he was Evil Morty when he evaded answering that question about who his original Rick was. Honestly, I wish that they didn't confirm that he was Evil Morty at the end so that I would get the chance to make a theory about him being Evil Morty and then get proven right later, but nonetheless, the ending was still epic.
The season 3 finale is called "The Rickchurian Mortydate" and the synopsis is that Rick meets the President. I'm almost certain that "the President" referring to the President of the Citadel aka Evil Morty, so Rick and Evil Morty will probably confront each other in the season finale.