If I understand correctly, If I understand correctly, you are going to use a magnet on one robot to pull up a relay and provide power to the other robot? That is doable, but I would think they would need to pull power from another set of rails. So you would need 4 rails, a set to guide the robots, the third rail to provide power to robot #1 and rail four to provide power to robot #2. I may be completely worng about what you are trying to accomplish.