These are really nonsense names. lol

Contrary to popular belief, modern propeller engines are actually constant speed, meaning that they spin at a relatively constant rate (once started up, around, say 2000 RPM, give or take a few hundred due to propeller pitch reasons) and the propeller pitch changes the speed the aircraft is going. This is different for the Cessna, which have a fixed propeller pitch and have viable propeller speed (can be as low as 500 rpm when idle and 3000 rpm when fully powered)

These aircrafts actually have 6 handles:
Left throttle
Right throttle
Left propeller control
Right propeller control
Left engine condition (fuel / air ratio)
Right engine condition (fuel / air ratio)
Usually the throttle is linked together but they should be also able to be able to be separated on certain models.

Agreed that mixture handle is mostly useless (unless a person want to save fuel or encounter engine fire and want to suppress fuel flow) and are ignored. (also, unless tried to change idle speed), but even if I combine those I still need 2 channels for propeller controls, which is not possible because Simpleplanes only have 6 analog inputs (activation groups don't count).

It's also that because the propeller pitch aren't extremely important they are not included in X-Plane 10 touch controls (but however can be changed by tap and hold their respective controls on the aircraft)
But those minor controls are still incredibly important.

There are also feather controls (the blades lie parallel to airflow, resulting in extremely large torque and stops the engines but enable easier gliding down) which isn't really possible in simpleplanes

These characteristics also means that these engines are incredibly picky and challenging to be in sync, but thanks to the fact that mose of these left and right handles are positioned closely enough that they can be moved at the same time.

Usually, you don't worry about the propeller pitch because there is this smart thing called "auto-feather" that automatically adjusts the propeller pitch based on the throttle and the speed.
Also contrary to popular belief (thanks to simpleplanes) the engines are directly linked to the piston engines behind them, so the blades turn even when the aircraft is not in motion (engine in idle is still turning)

And, therefore, if the blades were stopped suddenly for some reason (such as, say, hit the ground), the engine will be forced to stop for a fraction of a second which usually started the engine fire, which may or may not be able to be suppressed by cutting fuel supply (either via condition levers or fuel shutoff valves)

Quite a few of these aircrafts also have reverse thrust, so they can go backwards or stop quicker. Such as the Baron or the King Air. Avanti .... think Avanti also had it.

This is different from modern jet aircrafts, which don't require the propeller pitch handles. But, they gain a additional "engine bypass" or some air-leaking valve to