Hi ihstiv,
The main limitation with running two valves from one zone is water pressure. If you have enough water pressure, and if you have a standard irrigation transformer, both solenoids should lift without a problem. If you were going to do this you'd want to monitor the valves and the water output to make sure the valves were opening and closing and that you had sufficient water pressure. Controlling two low flow drip zones would work with good probability of success. If turning on two rotor zones though you'd definitely want to check your water pressure, and you'd want to monitor water hammer upon turn off - depending on flow, it's a lot of water to stop at once.
Jim