They're awfully close, aren't they? But, more to the point, I looked up 'canard,' and found this on MW:

"Etymology: French, literally, duck; in sense 1, from Middle French vendre des canards à moitié to cheat, literally, to half-sell ducks
Date: circa 1859
1 : a false or unfounded report or story; especially : a fabricated report
"

Will someone please tell me how in Sam's Hill does anyone half-sell anything?