Huh?
I have had two SXSs double on me.....but I had to pull the trigger first.
One was an old LeFever. It would fire both barrels if the rear trigger was pulled first. Worn sear.
The other was a single trigger Baikal IZH-43. My fault partly....had my finger on the barrel selector while hunting and, evidently had pushed it so that both barrels were engaged. Happened once.
Pete