i have this same question. I think the answer is that no one really knows and that it probably depends on your location.
I have read that you can get 2 phones with one reservation. I have read that you cannot as well. I have read that they might make you wait in the non-reserve line which is not realistic for most people.
It will probably depend on your given location and the policies will vary all over the country.
My wife isn't all that jazzed to get one anyway, so if she has to wait, she can wait a month or whatever. If i can get 2, then i will get her one. If not it gives me a chance to sell my 3g to pay for her phone anyway... win/win as i see it.