The aircraft travel the same distance.
The wind is nil. Wind is measured relative to the ground. Therefore the air at 40000 feet is entirely stationary relative to the ground and the air at 1000' is entirely stationary relative to the ground. The aircraft have the same TAS and therefore cover the same distance relative to the ground.
The points made by other posters about having to travel further when you are higher because of the larger circumference you are traversing is a red herring. The fact that the wind is nil compensates for this effect. (Basically the air at 40,000' is moving faster than the air at 1000' in order to remain stationary reference the ground.)
There is no mention in the question of a climb and there is no reason to assume the question refers to aircraft that start on the ground and climb to altitude. They could just as easily climb to altitude and get stabilised at the correct speed before beginning the experiment. And that is what the question implies.