Ps. Just to check that we're all using the same terms here: A 'Dead Cut' check is where you switch off the mags/ignitions one a a time to check primarilly for a faulty mag/ignition, when the engine will 'dead cut'
A 'live mag' check, is where both mags/ignitions are turned off to check that neither of them are still 'live' when they are both in the 'off' position.
I'm sorry but that seems to me to be exactly the same thing, unless in the case of the "live mag" check they are both switched off together, in which case, which one is keeping the engine running is unknown until a "dead cut" is done. Making the "live"check unnecessary.
Please forgive the pedantics.