The pilot stated that she was flying the airplane from the front seat, and the airplane owner (who is also a pilot) was in the rear seat. The pilot in the front seat turned final early to maintain aircraft separation and made a short and slightly steep final. She said she flared the airplane a little high and it bounced twice during the landing. During the second bounce, the pilot in the rear seat assisted the recovery by applying corrective input. The pilot in the front seat could not recall if she continued to apply control inputs or if the pilot in the rear seat had assumed the controls. Positive control transfer was not accomplished. The airplane subsequently ground looped to the right, substantially damaging the left wing when the wing tip struck the runway. The pilot reported no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation.