Have also seen a German double with a rolling block action, was around the NY gun shows a couple of years ago, it was an 8x57R or a 9.3x74R, looked a bit odd but handled well enough, well known maker, don't recall the name. Saw the Hagn double drop block at the Reno show a few years ago, both barrels made from one piece of steel, quite a stunt although Whitworth did it 150 years ago with his percussion double hex bore rifles.