No, it is not safe or possible for two aircraft to stay on the same runway at the same time. Runways are specifically designed for the takeoff and landing of aircraft, and they are meant to be used by one aircraft at a time.
Air traffic control systems and procedures are in place to ensure that aircraft are sequenced and separated appropriately to maintain safety. When an aircraft is cleared for takeoff or landing, it is given exclusive use of the runway for that purpose. Once an aircraft has completed its takeoff or landing, it must vacate the runway to make way for the next aircraft.
Allowing two aircraft to occupy the same runway simultaneously would pose a severe risk of collision, as aircraft need clear and unobstructed runways to operate safely. Air traffic control authorities and pilots strictly adhere to these procedures to prevent any such dangerous situations.