If memory serves me well, with an engine failure SF340B, things should happen like this:
a) the prop feathers automatically;
if not
b) moving the condition lever to cut off --> prop feathers
if not
c) manual feathering pump switch on
So in my opinion when you use manual feather the condition lever should be in cut off.
We used to do a test of the feathering sistem on the first flight of the day and it was posible to feather an engine running at idle if you weren't paying attention.