I have seen another Hauptmann shotgun with a .22 Hornet rifle barrel between the shot barrels, in that size and with the barrels closed is looks like a conventional side by side.

On the Dickson which has the 'pyramid' configuration, it has two triggers. The front trigger fired the bottom barrel then the right barrel and the rear trigger only the left barrel. Also, unlike the in-line configuration the triggers were not articulated and looked like a normal double trigger gun.