Bob Moore wrote in
46.128:

Bob Gardner wrote
If the switches are in parallel and one of them develops an internal
short circuit, you will still have trim runway; if they are in series,
both must be closed simultaneously. Sounds like a dumb idea to me, but
check with a mechanic or radio shop for a knowledgeable answer...I'm
not sure that I would expect the Chief Pilot to be the expert on
electrical questions.

Bob...if they are anything like I flew in the Boeings, one switch
powers the trim motor, and the second engages a drive clutch.

They're not the same. Actually, if you remember, if you got an out of
sequence operation of the two pickle switches (never flew the 70-, but the
others are lke this) you got the trim wheel brake to engage with a clatter.

Bertie