I had the chance to talk to the academy coordinator while I was waiting for my interviews. She said that although they will finish with USNA interviews in the beginning of November, she will wait for all interviews to be conducted before she takes the recommendations before Senator Warner. We would hear from his office around Christmas, but she did mention communicating with congressional offices. So there is a chance you will get a nomination from your congressional representative, but you will find that out after you get rejected from Senator Warner. They want to try and eliminate double nominations as much as possible. I know there can be some trouble with this depending on if your congressional representative uses the principal nomination system. She seemed very educated on the process though, and I cannot imagine that she would make a decision that would hurt someone's chances at getting an appointment. If this is a concern, then I suggest you talk with your CGO.
On a related note, has anyone received confirmation from Senator Webb's office of your application? I sent it in and got confirmation that it arrived via the post office, but they have not sent anything to confirm. I'm in the same situation with Congressman Periello.