That's because nobody's had the situation in which there's clones of people having sex with each other and cloning each other more and travelling to other universes to clone their alternate selves.
...I don't see how that is relevant to the issue at hand. And geez, there's
one clone!
Incorrect. Selina's fixation on TA!Angel is magical and possibly physiological. Her fixation on MG!Angel is only psychological. She has no real reason to, it only occurs due to issues with differentiating the two. I mean really, we could just equip Angel with some sort of obvious hair ornament and give Selina something that generates a sensation when MG!Angel communicates to her or some other way to differentiate the two.
What, MG!Angel's lack of a tail isn't enough?