I suggest talking to the breeder about why they bred the two dogs they bred. They will likely talk about that "repeating" dog", as that is what is called "line Breeding on this dog" some line breeding is pretty loose, ie. far back and some can be pretty close. This is usually done, for the breeder to produce a litter of consistent puppies (looking a like) and for health reasons, it allows for predictability. If the dog they line breed on, lived to 16 and didn't produce cancer often, the breeder is likely betting on this to positively influence the litter. Though nothing is guaranteed, so breeders line breed with caution, especially since there are no known way to track PU (that really bad eye disease that leads to glaucoma in goldens). What sometimes happens is called an "outcross" the definition varies on what is an outcross, but in essence it is a breeding of two dogs from completely different pedigrees(no repeating dogs till many generations back). Many breeders feel this is the safer way to go, because in line breeding though you are doubling up on the good genes you are also doubling up on the bad ones too. They also feel that the breed needs more genetic diversity to live longer.
Hope that helps. I can't give you a specific, this is too much, because it varies. K9data will give you a COI percent, which is basically an "inbreeding coefficient" many people believe that 15%-20% is the highest they are comfortable with, if I recall the discussion on this before correctly.