After extensive research, which comprised up to five seconds of heavy Googling, we have the answer: they became the off-brand, racist version of the Olsen twins. Observe!
Of course, one pair promotes a white nationalist ideology modeled on Nazism and works to exploit and strengthen an undercurrent of violent racism in American society, whereas the other pair is in a band called Prussian Blue. KIDDING. The Olsens never did anything worse than "Full House," and maybe murdering the Joker. Still, it's hard to say which pair is worse. (HINT: it is the racists.)
UPDATE: Okay, so one thing I hate - apart from the racism - is when I write something and then immediately think, "that seemed easy; surely no-one has made that particular point before, but perhaps I'd better check...?"
So, yes, okay, other people may have compared Prussian Blue to the Olsen Twins, but I'll bet none of those people have linked you to Prussian Blue Fan, a blog that appears to be maintained by Prussian Blue itself (themselves?) and contains photos of them hanging out at Natural History museums and getting ready for Homecoming that are somehow even more creepy than the band's official photos because the girls look so very normal and are not even wearing the Smiley Hitler t-shirts to signify that they are the Devil's own spawn. I, unlike those people, will link you to that blog. They don't love you like I love you.