My book states: "To prove that no real heat engine operating between two reservoirs is more efficient than a carnot engine between the same reservoirs, imagine a more efficient engine to drive a less efficient carnot refrigerator. For the combination of the engine and refrigerator you get a net transfer of energy from the cold to the hot reservoir without work being done on the combination, which is a violation of the Clausius statement." But what if i combine two *real* engines in the same way? This violates the Clausius statement too. Does that mean that *any*(real or reversible) two or more engines between the same reservoirs have the same efficiency? I thought that was only true for Carnot engines. help would be much appreciated, thanks in advance!