I consider a person to be a certain structure extending throughout space time. So, if two structures are identical, as in the loop scenario, I'd say that they were the same person. Of course, that's only if these accidental clones have the structure, which they will not, as one clone will be in position A, and the other will be in position B, and so be different people, albeit very similar ones. The same goes for the first scenario, they are going to be different people since they will be in different situations. In the case where they have the same experiences for the rest of their lives, and so the same structures in space time, they will be the same person. But that could only happen in two universal configurations which were the exact same... which is what will happen in an infinite universe. But might I ask, why do you not think that they shall be the same person?