I have sent identical letters to Jefferson and Lewis Counties Historical Societies. I have provided the excerpts from each reference and described the mystery of the two wives. I'm hoping they will be intrigued enough to do further research.
At this stage I believe the Jefferson County item is in error, however, I can't explain why Ellen Johnston McBride isn't in the census records of Archibald and Hellen Barr using the same birthdate.
I have considered that she might not have been a legitimate daughter.