^^^ what they said. You've got inertial triggers on your shotgun. The idea is for the recoil of one shot to reset everything for the other barrel, so that it is almost impossible for both tubes to go bang at the same time. My old Fausti had a mechanical trigger, so I didn't have to do that. My new Browning has inertial triggers like yours, so I have to flick the safety off and back on to fire the other barrel with snap caps or in the event of a misfire. It's nothing to worry about at all.