You obviously need a whole lot more research under your belt. Please get yourself a mentor in your chosen breed to help you along. Breeding is a science, not a pastime or a money-making venture. Lots of money, patience and forebearance is necessary if you're going to breed the right way and not add to the unwanted-pets problem in America (and around the world?) today.
BTW, it's "mating," not "mateing"; and "advice," not "advise."
It would appear that there has already been at least one tie, probably more. My suggestions would be 1) Talk to your vet 2) Talk to the breeder your purchased your dog/bitch from 3) start reading up now on the required care and preparing for whelping so that you can help your girl when the time comes.
In answer to your question, yes, a bitch can have eggs fertilized days apart.
***Edited By: pyrmom on 7/8/2009 2:59:14 PM*** Reason: *
"Some days you're the dog; some days you're the hydrant". author unknown