What does one do when two people ask one to prom?

Let me describe the people involved. The first I have known since middle school. I was a total dick back then, but over the past couple of years we have become friends. We hang out in sculpture club and sometimes walk home together, but aside from that we have only met each other outside of school a couple of times. She has never expressed any romantic interest in me, and has hormonal issues which, she says, make her not inclined to anything of the sort towards anyone. When she asked me, she basically presented it as, “Prom is an important part of the high school experience, and it would be a shame not to go, so, wanna go?” But, it is quite possible that she was making it sound more casual then she felt, because while she is not at all reserved around friends, she is shy about making new friends and, I suspect, about trying to move a friendship to another level. I was kind of caught off guard, but the way she asked didn’t seem to demand an immediate response, so I just said I’d think about it, make sure I don’t have anything scheduled, etc.

The second person sits next to me in one of my classes, and we chat whenever we see each other around school. Again, I never knew that she had any interest in me (either girls come awfully sly these days, or I’m just clueless), but today one of her friends, who I know about equally well, gave me a bag of cookies and a note asking me to come (this was right before an AP test, and I had been gone for other tests all week, so she couldn’t have seen me in person). I told the messenger-friend that I would have to think about it, and that I had been asked by someone else and would have to sort things out before I could reply. I am well aware that many people go to Prom as a social rather than a romantic event, and might have assumed that such was the case here, but after the test, the friend asked me again what my response would be, kind of nervously, and then said that the girl had been wanting to ask me for a while, but didn’t have the courage, and that it meant a lot to her for me to go.

Which puts me in quite a sticky situation. I had absolutely no intentions of going to prom, and the event itself is not at all important to me. I don’t have any particular romantic attractions to either of these girls, but I am no less attracted to them than anyone else; basically, I never had any intention of being in a relationship with anyone, so I never fixed my affections on any one person (except asmonet, of course). I am more concerned with dealing with the situation such that I don’t hurt anyone’s feelings.
So, anyone feel like helping me through this teenage emotional angst and drama?