(Just like planes)

Not at the same helm. It can be done but why?

Well as a matter of fact, yes there are. Some, off -shore racing sailboats have side by side ''wheels'' . If you take a look at Yachting, or Sailing magazines you will see pictures of them. However, most boats that have two ''wheels'' are flybridge cruisers. One in the main cabin, and a second on the ''bridge''. These are used one at a time.

Boats that have two wheels, or even three are typically separated by distance. One helm station (wheel) will be in the main cabin and a second helm station will be on the fly bridge ten feet above the main main. l have even seen a third high fly bridge another ten feet above that.

Yes, many have 2, 3 or even 4 control stations.
Double end ferries have a control at each end. Large AK crabbers have 2, one port & one starboard. Not many of the newer vessels actually use a steering wheel, it is a small lever control that energizes a hydraulic pump, solenoid system to control the rudder.
Some tug boats have a directional system for steering without rudder. Also there is a ''Bow thruster'' system for large vessels that give very close maneuvering control.

Yes some sail boat have 2 helms next to each other> for port or starboard tack> there a 2 station & 3 station on flybridge sportfisherman with a tower>

Sure. tons of them. GOOGLE for ''Hynautic Steering''. they make a very good hydraulic steering system that can use multiple inputs.

Yeah many offshore racing sailboats with larger crews have any where up to four steering wheels.