In July 1996, a new wake vortex category was created for the B757-200 which placed it between revised Large and Heavy categories. Shortly thereafter, the B757-300, stretched version of the B757-200, was placed in service and soon treated by Air Traffic Control as a Heavy aircraft due to its maximum certificated takeoff weight. This study examines the behavior of vortices from both aircraft during landing operations, and shows little difference between the vortices of the two B757 series. In fact, both measurements and theory indicate that B757-300 vortices decay somewhat faster than B757-200 vortices. Therefore, the B757-300 is being penalized by an unneeded increased wake vortex spacing during landing operations.