This is a spin-off enquiry primarily for davidr and ann. I note you say that "Menzies" is commonly pronounced "Mingis" or "Ming" as with the Liberal leader.
One of my ancestors, John Mearns Brown, was born on the Island in the 1820s, but his father came from Scotland, probably Roxburgh. There is evidence that the child was christened MEARNS, but when he was buried in 1907 the register listed him as Merrence. His son Arthur Brown had a baby that was actually christened Merrence but died 3mo old.
Old James Brown, from Scotland would have spoken with a solid Scots accent. The family bible shows that he knew how tro spell the name, but his wife was a Manx girl, and all the children were brought up on the Island, so unless they looked at the records, would presumably assume the name was spelled as it was pronounced.
Would a good Scots pronunciation for Mearns sound like "Merrens" ? If so, this may explain the existence of the wrong name in the 1907 burial, and a wrong spelling for the 1890 grandchild.
Any help from those familiar with Scot-Speak would be welcome !