Here's the Franz Joseph bridge plan I was talking about
As you can see, it incorporates the secondary door as seen in TAS, but has it leading to an 'outer ring' service corridor (also allowing the bridge crew access to the toilet). Not sure how that works in TOS where the secondary door patently didn't exist, though.... the gangway steps seen there are said to be the emergency foot access out of Deck 1 in the event of the turbolift malfunctioning.
George Steinbrenner wrote:
(Or perhaps the second door goes to a briefing room, like Voyager's does.)
Now there's a thought.
I do seem to recall that the scene before
we see Kirk enter through the secondary door, the scene is of him alone communicating with somebody over one of those desk mounted screens. It could
have been a conference room.....