Right of Way Industries (ROWI) made some 3-rail scale articulated steam locos with a vertical motor above each set of drivers. On these locos, both driver sets could swivel inside the boiler shell which of course is not prototypical. Note that every single HO articulated that I've ever seen has this dual-swivel arrangement.
In O-scale 2-rail, I know that some articulated steam has been built with two motors in the firebox. One powers the rear set of drivers using a short drive shaft and the other (typically stacked above the other motor) powers the front set of drivers using a long drive shaft and universal.