Moore is a fairly common name and in Arbory there were on average two births per year. Henry 1831 does not appear on the IGI. Was he from Arbory.
There is one aged 13 in the 1851 Arbory census whose father is John Moore. In the same houshold there is a seven year-old Elizabeth Corrin, John's granddaughter.
She appears to be the daughter of Richard Corrin and Ann Moore.
There is an Ann Moore christened in Arbory on March 1808. her parents are John Moore and Eleanor Harrison. Another christend March 4 1821 has parents John Moore and Jane Costain and athird Hannah, March 12 1819 has John Moore and Hannah Elliot. There is also an Ann moore born in Abory or Douglas on June 18, 1821 or 1823, for whom the IGI has as John Moore and Ann Preston as parents. All these IGI entries come from LDS members submissions rather than parish records and as such cannot be considered as reliable.
Henry is also recorded four times (Douglas and Arbory), with these same parents, always on July 13, 1828, which invalidates three of the Ann Moore submissions. again these are not parish records but LDS member submissions.
The marriage of John Moore is also recorded twice, again LDS member submissions) in Douglas (about 1815) and Arbory (June 8 1816).