Experiment: Magnet falling in a copper/aluminum pipe
Drop the magnet in each tube, and time how long it takes to travel the length of each tube. In the first few inches, the magnet will be decelerating as it induces a current in the copper tube. This deceleration will not be constant, as it will be velocity dependent. However, it is safe to assume that the length and time that it takes for the magnet to reach a constant velocity will be the same for both tubes.