(a) The demand for a physical examination under this article and the response to it shall not be filed with the court.
(b) The defendant shall retain both the original of the demand, with the original proof of service affixed to it, and the original response until six months after final disposition of the action. At that time, the original may be destroyed, unless the court, on motion of any party and for good cause shown, orders that the originals be preserved for a longer period.