Gonna pull an idiotic theory out of my ass rn
Rick Prime has regenerative abilities because he's a vampire, he's able to be in multiple places 'cause of vampire teleportation. Motherfucker regularly flies around as a lil space bat and feasts upon other Ricks to stay alive.
This also explains why he hasn't aged a day since offering Rick C-137 the portal gun spiel.
Also the whole mystery of Rick C-137's and Prime's relationship prior to the killing of Rick's family can be summed up to a homoerotic vampire/human entangelment where Rick is both Prime's lover and his blood bag.