The advantage of this secondary one is that it is driven a different drive train, if the engine stops for what ever reason, the standby gene keeps turning as there is a bypass gear train in the gearbox which keeps it generating.
So that would bypass the freewheel unit as well? Don't think so but hey in 45 years of fixing and flying them I learn something new every day. Mostly that a lot of people haven't got a clue what they are talking about!