I have had double discharges with my .45 NE mostly before the trigger was fixed. I also started to use the rear trigger first when I thought about it.

One feels a heavier push in the shoulder. And usually one has to take a step backwards. I know then or suspect it was a double discharge, the step backwards is the tell.

No throwing the rifle out of my hands while some idiot.

A lighter person might feel it more. But one must be really limp wristed to have the rifle fly out of one's hands like that.