The skittish one, if indeed female, should relax as she grows. Some can be skittish when small for sure, but I have never had an adult female that was skittish...in fact most MM's aren't as skittish as one might expect IME.
@cold blood I'm pretty darn sure that they're both female. I need another molt to confirm, but I'd be surprised if either turns out to be male. I love having these batches from the same sac, very interesting to see differences in disposition.