The CFI simulated an engine failure on the right engine during takeoff after having simulated a left engine failure during the landing approach. The left engine failure was simulated with the left throttle retarded during the approach and landing. After the throttles were advanced for takeoff, the CFI simulated right engine failure at 85 mph by using the mixture to idle cut off. When the student responded by closing both throttles to land straight ahead, mixtures and throttles were then reportedly advanced and the aircraft climbed to 100 ft at 100 mph. A witness reported the aircraft with the right wing high, drifting left, and then suddenly leveling the wings and nose down to ground contact. The CFI said he took over at 85 mph as the aircraft turned left, rolled both wings level, closed both throttles and landed off the runway. The landing gear was coming up at touchdown. The CFI thought the left engine may have loaded up and not responded during the last takeoff.