Yep; the old, (but NOT forgotten) DD could be configured up in many strange ways. How about trannies at both ends..along with two clutches? How about a marine tranny on one end and a big generator on the other? Or...the oil platform special which I saw once. A mighty DD standing on its end with a big alternator on top...or bottom.
Our old fire apparatus had DD's with two, (2) starters...seems one was not good enough. Or pancake models, (80 degrees on left side) with a very flat top and bottom...thus its nickname. Crown Supercoach schoolies used a lot of those; also marine. Sportfisher yacht guests couldn't figure out where the mills were. HB of CJ (old coot)