I just saw that the Riftborn can build a colony ship with more than 1 colony modules, is there a point to having more than 1?

I'm in no way sure, but I imagine it would mean the ship would not be deconstructed and you would be allowed to move it to the next system for the second colonization. I imagine it would be deconstructed at that point, though.

Side-note; coming from Endless Space 1 and other 4x games, I was a bit surprised you can't instantly colonize multiple planets in the same system if you bring multiple colonizers. :O