The aircraft owner, who had not flown for one year, and a flight instructor were on an instructional flight to prepare the owner for a flight review. After flying about one hour, they returned to the airport and began practicing landings. After the second landing (a touch & go), the left engine lost power shortly after takeoff, but it was too late to abort and land on the runway. A witness saw the aircraft yaw at about 150 feet, but could not hear it over other noise. According to him, the aircraft entered a descent with the propellers still rotating. The aircrew stated that the right engine seemed to lose power as the glide became steep. A wheels-up landing was made after crossing over trees. An investigation revealed that both fuel selectors were positioned to the auxiliary tanks and both of these tanks were empty. Both pilots stated that no attempt was made to change the fuel selector positions after the loss of power.