On a quick check, --ists an MRC Tech 4 Dual Control for about $60. Google would show other places they can be had. That might be the fastest way to solve the problem, but like people have said, trainshows, swapmeets etc might save you a few bucks.
BarstowRick is absolutely right. You're only asking for headaches with a dual control pack in this application. Perhaps you can use two power packs on two stacked shelves and/or get two with smaller footprints (or more, to reduce the overall area used), like maybe the Kato or even the Maerklin Z ones (10V max).
Thanks so much. Oddly enough at the local trainshow this year here I didn't see anyone selling new or used dual power packs of any make. I was looking really intensely to find one too. As for swapmeets, there never seems to be any around here. I could get an MRC dual power pack from z-scale monster trains, but it costs over 70 bucks and add to that the shipping costs, well we are now in to the 90's i'm sure. Far more then I really want to spend. Perhaps I will have to go with two packs instead. I don't like this idea of robbing power from one side to power the other. That's what I wanted to get away from. Thanks for all your input. I'll have to give this some re-think. Ken