That is the crux of this thread. It would seem that the people writing the closed source drivers don't understand when voltage should or should not be sent to the LNB... or there is not sufficient flow of data from enigma to the driver to be able to work this out... or just coding incompetence.
In the case of the GB, voltage is being switched on/off on the root tuners irrespective of whether one of the link tuners is in use.
In the case of the VU, voltage is always present on socket A (but according to Sicillian's testing it is not clear what is going on at socket B).
As we haven't got access to the closed source code the only way for us to know what is really going on is to test the voltage supplied by each socket with a multimeter.