Well, I vaguely recall that song, and it never seemed to me that "Hubbard" was of necessity a last name. There are many examples of "front" names being interchangeable with "back" names, my own family name, Clayton, being a good example. I had a classmate years ago named Clayton Shank, so when someone shouted, "Clayton!" on the playground, we'd each respond, "What?"

So, in the tradition of Bascom Lunsford, I'll just say it's a country way of naming, and it could easily have been the MCP's first name. For that matter, some folk are just known in their community by one name, and it can be the first or last, it don't much matter. So another possibility pops up, right there.

We're not likely to ever learn, either.

Bob