Check the tattoo in both ears of the animal.  They should exactly match the paperwork, EXACTLY.  Write down the animals registration number and the organization that it is registered with eg: ABGA,USBGA,IBGA.  You will be able to look the the specific organizations website and input the registration number in the animal registry search area...Again the information should match the paperwork EXACTLY....If all this matches the goat is probably legit....Possible explaination: the seller isn't a member of the organization that the animal is registered with and never tranferred the papers over to himself as the new owner.  He instead used the white out to cover his name and information that was filled in by the breeder of the animal.  So if you look up the registration number and the breeders name appears as the current owner you have your answer.  Any more indepth than that would require a call to the registry to clear up any confusion.....CHECK THE TATTOO...I have seen many goats/horses/dogs/etc. passed off as a different animal and sold without any knowledge of the deed unless you carefully check the papers against the animal. 
  If you really want to check out the animals registration I can give you the number of the general executive secretary/ vice president of the USBGA...She will have the answer. PM me if you want the info