while i by no means know all the controllers out there those that i do know of are usually designed to prevent what you would like to do. there is a way around it if you want a semi-permanant solution. you take the wires for each station you want to run together and hook them to the same station in the clock. a more permanant way is to hook both valves to the same wire.

Yes, I'm finding out that may be the only option. I was hoping to make it an optional setting, but may not be possible.

one thing you can try if your current controller has multiple programs is to set the stations on seperate programs with the same start time. sometimes with older controllers this trick will work.

The DIG 8006 will run two stations at the same time with durations from one minute to 12 hours and it is inexpensive. I think it was designed for drip irrigation, but the valves don't care.