golden retriever puppies

Question
we are about to purchase a golden retriever puppy.  the litter we looked at has several dark puppies and some cream colored puppies.  the mother is dark and so is the father.  i know dogs can have different fathers, so i wanted to make sure the father is who they say it is.  i don't want a mixed breed.  is it possible for 2 dark redish golden retrievers to have cream puppies?

Answer
I guess I haven't seen enough Golden litters to give a good answer.  I know yellow Labs can produce a variety of shades in one litter.  

I will be seeing a ton of puppies this Saturday.  In some cases it will include the parents and several litter mates.  Most of the breeding will have taken place in a highly controlled kennel and the females protected until past their fertile period.  I will also have a chance to talk to the people who keep the mothers.  

You are right, that you can not count on the male a female was known to be bred to being the father of all the puppies in the litter.  My vet tells me about some of the improbable looking ''purebreds'' he sees.