Hi Shera
According to the IGI there are two births registered to George and Martha for a son called Joseph - the one in 1813 you found and the one in 1816 that the name was hard to read. I wondered if the first had died and they named the next son the same name, which I believe was quite common in those days. Do you have access to any burial records for the church for this period?
Finally on the IGI there is also a daughter to George and Martha, also called Martha - born 29th August 1811 and baptised 6th Jan 1812. Can you check if this is correct for me?
Many thanks once again