Speed matching! Doesn't it take the fun out of railroading? Now if you talking about having two engines on the same track and you want these two to stay spaced apart as they move around the track, that's one thing. But if you are using them in a consist configuration, that's where all the fun is. You can take either the first and/or the second engine and manually control their speed as a part of the fun to keep them at an equal stance with one another. The real fun comes in descending or ascending a grade where one will engine may need assistance to support the other. To me that's a lot of fun keeping pace with the movement of the entire train, and it's an artist that can control both engines, keeping them from jerking along, but produce smooth movement.