Wade wrote:

If, at idle, you turned off the left mag, and noted an rpm drop,
then turned off the right one, and also noted an rpm drop,
then doesn't that confirm the same thing as turning
both of and feeling for the engine to start to shut-down?

No. Turning off the left mag verifies that that position of the switch will
ground out the left mag. Turning off the right verifies that the switch will
ground out the right mag in that position. You can only verify that "off" really
grounds out both mags by turning the switch off.

George Patterson
"Naked" means you ain't got no clothes on; "nekkid" means you ain't got
no clothes on - and are up to somethin'.