The chance of running into two alien species in one day seems pretty unusual. Perhaps it means something?
That is precisely what makes me think they are sockpuppets of a single entity (even within the story Universe, not just in the sense that Elizier invented them).
Probably I have watched too much Star Trek but it is hard to shake the suspicion that both the Superhappies and the Babyeaters are sockpuppets for some kind of weakly godlike entity messing around with us for a laff..