The flight instructor and the commercial pilot, who was undergoing multiengine instruction, departed the airport traffic pattern and conducted flight maneuvers for about 30 minutes on their way to the destination airport where they planned to conduct some practice landings. During final approach, the instructor reported the pilot was maintaining a stabilized approach with a nominal descent rate and airspeed. Upon reaching the runway as they entered the flare and the airplane was in ground effect, the flight instructor stated, “power idle" and the pilot pulled the throttles back. The airplane touched down firmly on the centerline, then immediately began yawing to the left. The pilot attempted to correct, and the instructor told the pilot to stop “dancing” on the pedals, but the pilot overcorrected, and the airplane went in the opposing direction and off the right side of the runway through the grass and across a taxiway before coming to rest. During the impact, the landing gear collapsed, and the wings sustained substantial damage. The flight instructor stated that there were no preimpact mechanical malfunctions or failures of the airplane that would have precluded normal operation, further stating that she should have reacted sooner when she observed the beginning of the loss of control. However, the airplane was only equipped with brakes on the pilot’s (left) side, which limited the flight instructor’s ability to correct the pilot’s actions.