On the face of it, it's a puzzle why Joseph and Judith would grow up together in North Farnham Parish and go all the way to Bedford County to get married.
But my guess would be that Judith is Judith Unknown really, and she's been found some parents with her married name. It's very common out there in the jungle.
As for the dates of death, there's a possibility that John remarried. The death records wouldn't give the maiden name and you can't trust anything that's not in the original records.