Huntersdad:
I've own two droplocks: A single trigger and a double trigger. Neither has ever doubled on me.

But before you go blaming the gun, check into yourself. If you do not hold the gun firmly in shooting it, the result may be that your trigger finger goes a bit "loose" under recoil and fires the gun twice -- as if it were doubling. I especially suspect this since there has been no recurrence in your gun.

If you still suspect the gun, there is a Westley agency in Montana.

Best, Kensal