Typo on his surname on the Find-a-Grave entry.
You have to remember, often the spelling of names was never an issue i.e. whatever was considered correct was what was written down.
As an example, Iain/Ian, MacDonald/McDonald, no questions asked.
Nowadays, time is taken to verify the spelling of names unlike previous times.
With the advent of computer data, it's so much easier to verify everything, however, many people did spell their surnames different to the spelling on their baptism/birth details.
Settled spelling of names seem to have come around in the early 1900s when people were more literate.
I've seen different spellings of names on the same document in the past!
Annie