It's extremely telling that the Bull refers to Pelinal as "uncle", since Lorkhan would indeed be the uncle of a nephew of Kynareth, in a way. From this perspective any and all incarnations of Shezzar before or after Pelinal are for all intents and purposes the same person. (A certain comment made by Pelinal seems to imply that for Shor, time is not linear. He vaguely remembers the player character, but doesn't remember if it's from the past or the future and even disregards it as irrelevant. I have my own theory that he recognizes the player himself and not the coc, meaning that as he has CHIM he can see through the screen and into 'our world'. He would remember you, the person playing the game, from when you played Morrowind and freed his Heart.)
Here's my take on that: Shor is outside linear time, this is true. That's because he is both himself and Akatosh, who is himself time and therefore not bound by its linear perception. As such, Pelinal's spirit (as in the part that was just Pelinal) recognized you as the one who would mantle him because in the future you were him.
which leads to a question, is it different to mantle Shor than someone else? Since you technically mantle pelinal, but pelinal is shor, so is the CoC a shezzarine?
I apologise, my shift key isn't very good.