Thinking back...most of the sets of fraternal twins I've known have pledged different groups and most of the identical sets have pledged the same groups.
There are actually 870 PNMs signed up for sorority recruitment....
A few years ago there was a set of twins and both went DG. Then another set came through and one went Chi O and one went Tri Delta. There were triplets in Pi Phi when I was a freshman back in the day. There were twins in AOII when I was a freshman too. It's always fun to see where the twins end up!
At least when I was in school, sororities would take out an ad in the student newspaper after bid day with a list of their new members. Don't think those are still published.