Tokyo Subway: Two Conductors?

Ifve been in Tokyo for a few days now (enjoyed it so far) and have been riding the trains a lot. Ifve been sitting the back watching the conductor and realised that there are two. One seems to do more than the other, he presses buttons and does the point-and-call on the platform. The other doesnft do much at all. Why is this?

It may be training/supervision. Other times they are just catching a ride to work - they do that sometimes.

Or are you meaning the conductor at the front and the other one at the end?
Most trains in Japan, except those calls gwanman=one man carh have two conductors. One at the front who is driving and the second at the end who announces the stations and helps with departure. (And probably does a whole lot of other tasks as well. )
Seeing two conductors in the same conductor room is not standard but does happen as PP said.

Continue enjoying Tokyo!

One at the front who is driving

That is not a conductor, but a driver.

The reason why there are two people in rear car is actually when it is simply moving btw stations.
It moves because the yard and of the train and the station
and the resting place/office of the crew(driver, conductor) are different.
Also there are many cases delivery of documents, lost items of passengers etc btw different stations.

If a combination of young conductor and veteran crew with is the training.
If no working other one has a bag(basically bigger) with timetable(called "staff") is a driver.
http://www.tobu-kids.com/job/untenshi/tools.html
This is two drivers in front car case at different rail companies through service train border station.
https://youtu.be/fr8NUC7uGUw