Thomas Borchert writes:

Just looked, and the MSFS Baron does NOT have a BOTH selector position.
The real one doesn't either, neither does the Bo.

The Dreamfleet Bonanza has such a position, for reasons previously explained.

The Dreamfleet Baron has a system that feeds each engine from its respective
tank(s), with the option of a cross-feed if required. As far as I know, this
is the same as the real thing.