I might be wrong.
I remember being shocked seeing Immortal in season 2. I thought Omni-Man had killed him again in the final fight in season 1; punched right through his abdomen or something. The people watching the broadcast gasped and all when it happened.
Did they just make ANOTHER clone of him? Or did he not actually die in that fight?
You need to remember that he’s basically Vandal Savage in terms of his powers; i.e. doesn’t age and can heal from almost anything
He was first killed by Omni-Man is S1E1 via a hole through the chest and then decapitation, but then he was brought back via the Mauler Twins realigning his head to his body in S1E7, allowing it to reconnect and for him to heal.
He was then killed again in that same episode by Omni-Man again, being torn in half at the waist. But then at the end of S1E8, we were shown that Cecil took his body and arranged him in a way that allowed his upper and lower half to reconnect, healing him yet again.
The death we see in the alternate universe in S2E1 implies that he can’t come back from having his head destroyed, and Season 1 implies that he can’t come back to life after decapitation or being torn in half without external assistance.
He is not a clone, he’s just the same dude who got Frankenstein’d back together a few times… minus the green skin and stitches.