Duck, Duck, Goose is a common children's game but a typical Minnesotan calls the game a slightly different name: Duck, Duck, Gray Duck. I have never talked to anyone outside of Minnesota that knows of this game as Duck, Duck, Gray Duck.
Wikipedia merely notes that it is a Minnesotan variant:
"Duck Duck Gray Duck" is a variant played by children in Minnesota. The core gameplay difference is that the picker taps the heads of the other players while calling out variant colored ducks and then calls "grey duck" in place of "goose".
There are no notes on why the game is named differently or why Minnesota seems to be the only region that uses Gray Duck.
My question is: When did Duck, Duck, Gray Duck diverge from Duck, Duck, Goose and is there a particular reason why it did?