Air Compressor: What would "twin-cylinder" mean? I'm figuring out details about an old compressor and it's made by a Greek Company. I can't find too many details but one part that confuses me is it says "twin cylinder". Picture below. Specs say: Oil lubricated twin-cylinder, three-phase compressor belt Air receiver: 1000 Lt Power: 7.5 HP 7.5 Suction: 1900 lit / min Pressure: 12 bar Voltage: 400 Volt Dimensions: 2330 x 800 x 1460 mm Certification: CE & TUV Hellas Warranty: 12 months [Broken] It doesn't look like a twin stage unit. What's the function of two independent compressor units on one tank? Redundancy? Or they run them in parallel? Can anyone comment from the photo? Would the tank be one large 1000 L or a split one? Wondering if anyone has seen similar units.