Two captains on the bridge

One of them was acting as chief mate today, the opther was captain, same with us "downstairs", two chief engineers and one of us was chief today, according to the muster list where every crewmember must read what his or her duty is in case of emergency. 
As usual at the trips with contributors of our ship is the interet that every one has, and: wheelhouse and engineroom are free to enter.