1 Reason Why Evil Morty Isn't Rick's Original Morty (And 5 Why He Is)
6. Why He Isn't - It Might Be Too Convenient
The issue with all of this is that until it is a proven theory, it remains hearsay and conjecture.
Rick and Morty is one of the only shows, other than something like Futurama, that can simply dispel with something that is seemingly important by using its setting to throw it out as quickly as it can be thought of.
This has been the case on a few occasions, for example when Rick just shifted him and Morty to a new dimension because they wrecked the old one beyond repair. It's a very easy and obvious answer that they take because they can, though there are aforementioned caveats to it.
Rick can just pull a solution out of thin air and use the show's multi-verse premise to explain it away in a second. So, is the Evil Morty theory just too convenient? It has had many things that point in that direction, but this could all just be one big red herring.
Evil Morty being the original Morty of our Rick might not be a good theory for this show just because it's too obvious a road to go down. Especially with a series that uses the obvious to its own end, often ending up in a mixture of the obvious and the totally off the wall.