A random thought here, but don't the two timelines need to be distinct due to the presence of Alexander? At some point in the future Alexander is going to unfreeze from his time bubble and travel back into the past to deposit Dayan and Mide there to found their tribe which eventually leads to the events of the modern day that precipitate Alexander's summoning to begin with.

But because there are two timelines there should now be two versions of Alexander. Ours and the one in the 8UC timeline. So if the timelines are supposed to be one that branched due to G'raha, how can two Alexanders travel back in time to the same place along one timeline to do the same thing, with two pairs of Dayans/Mides?