Most of my BPs get multiple mice at a time, since I'm not big on feeding rats (for a number of reasons). One of my yearlings will ONLY take mice, and she's now getting anywhere from 2-4 weekly... I feed live, so my process is to put one in each tub, wait until they're done, do round two, and so forth until everyone's had their fill. It's a bit time-consuming, as it can take up to an hour to feed all 9 of them, but this works for me.

So no, there's nothing wrong with feeding multiple prey - at least not in my experiences. They're all growing like WEEDS (one baby's gone from 93g to 670g in 4 months), so clearly it doesn't affect their growth either. Just make sure they're done with the first mouse, before introducing the next... I mistakenly added one too soon recently, and almost caused a regurg when he was interrupted by the new mouse. Not good!