The reason I know is very simple - my own grandfather was known by both names, as was his brother and his father.
What is more interesting is your Peter below. Are you ready for this?s ....... I'm sure he's from my line as I have a Peter who was born around 1900 to Patrick Chapman and Mary Furlong (his first of three wives). I have other information on his early life but none on his later life although I feel he and his brother Patrick may have moved to New York.
I'd love to chat offline if you'd like to pass on your email address. I can even take you back four or five generations from your Peter. Where are you?
Eileen (Sydney, but from Wexford)