Feather or not
I do not think there is much differences.
In a twin if you loose pressure the prop should go to almost feather (low RPM)
In a single if you loose pressure the prop should go to fine pitch (high RPM)
The reason for the the twin is obvious, for the single I guess they want you to still have the option of starting the engine since it is the only one you have.
In the other hand, the twin will not totally feather unless you move the prop to feather BEFORE it reaches the minimum RPM. And putting a full feathering system in a single would cost more money.