Duplicate girls shouldn't cause crashes (at least, they used to work fine - you'd just get multiple copies of a girl in game) - if I remember, I'll test to see if that is the case. The blank girl problem is either a bug we haven't encountered before (seems unlikely), a problem in the distribution (possible, but again unlikely as no one else has reported it), or there is something corrupt in the .girls/.girlsx files. If you post the ones you use, I can take a look at them and see if that is indeed the case.