I've never done it myself but I'm sure it would be effective so long as it's during the peak of the rut , any other time during the rut it might get reactions from other bucks
but during the Peak rut, the Dominant Buck has already established his turf and the other bucks are less likely to stand up to other intruders but the Dominant Buck won't hesitate on his own turf....
So yes I think it would work providing it's during the peak Rut and the decoy is a nice Racked Buck..
Democracy is two wolves and a lamb voting on what to have for lunch.
Liberty is a well-armed lamb contesting the outcome of the vote.