"According to Marc Savoy there is no difference between a one step and a two step."

Yeah, but other knowledgeable people disagree. Austin Pitre was recorded in an interview by Ralph Rinzler of the Smithsonian Institute explaining the difference between a one-step dance and a two-step. On file at ULL (USL) archives of Cajun and Creole Culture. He's a generation older than Marc Savoy. Allie Young (even older) also distinguished between a one step and a two step.

The difference might be unrecognized by accordion players, but there are (or were) dancers who knew the difference. I hear a lot of difference between Hathaway Two Step (which I understand is really a one-step) and Fee Fee Ponchaux, which is a two step. Both are very old songs. Good songs for comparison. The older songs are where I would look to trace the complexities and the developments.

Agree with Bryan and others who mentioned it. Song titles are not a good indicator.

Just having fun

What's in a name?
To squeeze or not to squeeze, that's the question.

And in A. Savoy's book, Joe Falcon says he had a hard time trying to convince one of his musicians that there is such a thing as a "two-step waltz". "Colinda" is one (from J. Falcon).
La valse à deux pas (ou valse à 2 temps) :

http://en.wikipedia.org/wiki/Valse_%C3%A0_deux_temps