But I'm saying they can't separate because they are THE SAME PERSON. This scenario is extremely similar to Malacath situation because the two entities can't really revert back to their former selves without some curse being involved. That said, they can't just separate; they are the same person.
Try to stop looking at the label of Prince of Madness as defining SHEOG. That title is nothing more than words created by mortals; as V'vehk said: "all words are based on meat." SHEOG is just the personificaton, if you will, of Randomness and the Sithis-shaped hole (that is the Serpent constellation) that was created when Lorkhan was "killed" and when true Existence began. Because the Exactness (that is Jyggalag) was gone from the Mundus because of the unpredictability of Existence, JYG "flipped" into SHEOG.
If the CoC is indeed SHEOG, then two "Daedra," that is, entities that did not give pieces of themselves to Existence, that personify opposing ideas, Randomness and Exactness, are inside of Existence at the same time... which doesn't make sense.
Akatosh and Lorkhan HAVE to be the same person because they need each other to survive AND no one has seen them together in one place...ever. I brought that up because it seems apparent to me that you claim that entities such as these two can separate and exist separately, which doesn't make much sense because they are the same person.