welcome to Manx genealogy - names uncommon off Island are often common on Island and at this period often very common in specific parishes, Rushen was quite 'insular' in this respect as most married within the parish also first names were also drawn from a rather small pool - children appearing well within 9 months of marriage are again very common (look up the Manx illegitimacy law of the time - couples had 2 years post child to marry and still have child legitimised).