Have a similar situation with a Mallard I bought at TSC, they are a light grey when the other three are super dark. I few super awesome folks on here have given me some suggestions as to what it could be but I am the same as you just excited to see how he turns out.
I have been wondering this myself, the clearance ducks tug at my heart strings anytime I go in but I just cant take anymore. A google search of where the unsold ones go hasn't yielded much info :(