1965 alternator switch

[JB78382]

The split rocker switch that controls the alternator allows the front alternator to be taken off line, and leave the rear alternator on line. However, it does not seem to allow the reciprocal function ( turn off the rear alternator and leave the front alternator on line) . Instead the right (rear) alternator switch turns both alternators off.

Any ideas on why this is?

Cheers!

Jerry