I live in Drummaul and there certainly are and were both McCann & Moore families in the area. Looking at the RC parish records in a history of the parish entitled “Sweet Drummaul” by John O’Kane, I see mention of a Patrick McCann aged 22, from Lurganwest townland, migrating to Glasgow in 1837. The parish council in 1851 had a Henry McCann senior & junior on it. Arthur, Henry, Bernard, William, Harry, Bernard (Hart) McCann & Patrick McCann, all living in Ballealy & Mountshalgus were mentioned in 1848. So no shortage of McCanns, and nearly all in the one townland.
No Moores in the congregation. But the name is common in the area. I looked at the 1901 census and there were 33 in the immediate area, nearly all Church of Ireland. Could the marriage have been a mixed marriage perhaps? I did have a quick look at the baptism records in case there was an adult baptism (for Agnes changing denomination) but didn’t see one. So can’t say that’s the explanation. But it might be.