How does Sollux being derse and prospit work?? Does he choose which one he goes to, or what dictates which one he goes to when he falls asleep?

He woke up on Prospit first, but kissing him after dying made him awaken as his Dersite self. So it seems that people with two Dream Selves will wake up on their non-main Dream Moon first, and resurrect as their Main Dream Moon self.