Hmm, my VH doubled!?

[J.B. Books]

I had a 12ga Trojan double once, with two 1 1/4 ounce of bismuth loads which was a real attention getter. It flattened the greenhead I was shooting at. The giant kaboom echoed across the bay like a howitzer went off. In my case it was a worn sear. I was able to determine which barrel by shooting a 1 1/4 oz lead load with a primed empty hull in the other chamber. That way I could tell when and how it doubled without the punishing recoil.

[William Machauer]

A few years ago I was shooting bunker, normally I shoot Perazzi MX8s but a guy showed up with a Beretta SO5 that fit me perfectly, he said it's for sale and I could shoot it. So I grabbed 2 boxes of shells and proceeded to shooting a round. About halfway through the round that SO5 doubled. I shot a couple more targets and it doubled again. I put it on the rack and went for my Perazzi to finish the round.
I'll delve deeper into my Parker but I'm reasonably certain it was a fluke thing.