Stev-O nice link. Yes its a single head, with two bores and uses one Carb. very interesting setup. here is what a guy posted in a kawi forum that im in. The pic below is not the exact engine, plus its miss a section that has the 2nd spark plug that screws in from the side.
" The rear piston has the transfer ports and handles the intake and crankcase pressure, while the front piston discharges the exhaust, plus closes the intake, and is several degrees ahead of the rear piston, but both are on compression stroke in the combined compression chamber. This engine was designed specifically for the Austria landscape meaning it developed a lot of torque low in the rev range and had a very low ratio first gear suitable for two up riding in the mountainous country. it is very unlike most two strokes where revving the engine produces a lot more power. With the Puch you shift the gearbox in the low rev range and let the torque move you along."