One smaller one for the landing and leaving scenes, one thats proper sized for the astronauts to interact with and the other is the backup in case something happens during filming.

One lander for the astronauts, one for the film crew and a third one for the cameras, lights etc. You know you can’t just walk into a RadioShack on the moon and ask for a camcorder, right? Because in because in space noone can hear you ask.