Well, that's very interesting... never knew that existed. Here I thought I was being innovative by hiding an additional clockwork motor in the occasional Marx tender:
...and I do run the occasional long trains on my windup layout using distributed power, usually with one locomotive on the front and the other at the rear as a pusher. It actually works well; the trains aren't too particular about how they are made up or where the 2nd loco is situated. The tough thing to do is start both locomotives at the same time when they are more than an arm's length apart!