The primary design consideration in placing a secondary bridge is seperation; you don't want a hit that will smash the bridge destroying the secondary as well. This would include every ship from Heavy cruiser in ocean warfare up to battle ship. Considering the size I think the vessels in Star Wars would use the same meter.
Such ships as the Acclamator, especially considering the size of such vessels in Star Wars, they would also have both secondary and Flag Bridge where admirals would command from. On An Acclamator I would suggest that because of their dual purpose, both troop and transport and warship, that one, more likely the Flag bridge would be directly below the bridge on a deck about five above the keel. The other would be forward of the troop landing bay.
But it is a design consideration made by the designer himself. If you look at a cruiser of the Prinz Eugen of WWII, you have the normal bridge, with the secondary bridge below the aft gunnery station.