Explain This One To Me...

So I was hanging out with one of my friends in her office on campus. Because of the difficulty in locating stairs, you always have to take the elevator in her building. I noticed these buttons in the elevator.



One set of doors, two "door open" buttons? She pushed the door closed button when we got in, and it stayed lit until the doors closed, but I didn't have the nerve to press the rest of the buttons just to see what the difference was between them. Huh.