Sorry you haven't had any responses yet, but have you tried doing a search? This question has been asked quite frequently and recently as well.
But in general, the conventional wisdom is:
1) you do not have to write two separate personal statements if you don't want to as long as the one you do write and send to both specialties is non-specific enough (ie, don't mention your love of surgery when applying to anesthesiology)
2) you do not have to have two separate sets of LORs sent either as long as the letter writers do not mention what a "great surgeon" (for example) you'd be when you are applying for anesthesiology positions as well
3) programs will not know you are applying to two different specialties except in the off chance that you are applying for two different specialties at the same program and some faculty members find out, or even at two different program and your name comes up. Again, pretty rare occurence, so most don't even worry about it.
Do a search through this forum and you'll find others who have answered this question.