I also noticed the same birthdates! Dogs born in January and sometimes December by a commercial breeder rarely go into the pet stores as there is little demand as they can no longer be Christmas or Valentine Day pups! Usually only if the breeder also sells online do the pups get sold to puppy buyers and not to other breeders. I am surprised that he kept so many possibly related dogs! My Arnie was born in early January 2001 and only two from the litter went to pet stores and one was returned so 5 out of 6 were sold at the auctions. I bought some females-10 months old in Fall 2002 who were sold at an auction because that year there was too many B pups and the dealers/brokers were not buying any so the breeder sold them at auction. Bambi's litter was born December 13 2006 and none of them-4 in the litter made it to a pet store and the breeder was also a dealer/broker so she could have sold them directly.
Jennifer