Well, I found this alternate chorus in the Rise Up Singing songbook

(Canadian chorus:
This land is your land ...
From Bonavista to Vancouver Island
From the Arctic Circle to the Great Lake Waters
This land ...)

I found the same thing in a cute little booklet called Nova Scotia Seniors in Song, a less-than-scholarly work, but at least it's from Canada...
Don't know if there's more. In the lyrics I found, there was just the different chorus, but the verses were the same.
-Joe Offer-