Does a sexual union with one's body incarnation of an opposite sex count as a misconduct?

According to Mahayana doctrine (at least within Nyingma linbeage), different incarnations of body, mind and/or speech of a same sentient being are possible. By which I deduce that a sentient being of a lower realm could also be reborn into a human realm having, say, two bodies of opposite sexes. Hence, given the conditions listed, my questions will be: a) Can a same sentient being be reborn in a human form in two or more body incarnations having opposite sexes? b) If yes, would a sexual union between, say, two such body incarnations of a same sentient being having opposite sexes in a human form count as a sexual misconduct, provided the other requirements for a proper sexual conduct are met? Any reference to a sutra and / or abhidharma text would be of a great help.