Multiple characters in Band of Blades

Band of Blades’ back cover describes a range of different character options. However it is advertised as 4-6 players, and many of the groups of character options have widely varying numbers of options available.

For missions you appear to be selecting from Rookie, Veteran, and five different specialist roles – so seven options.

But for other parts of the games it lists other numbers of options – always less than six. E.g. There are only five Legion roles, there are only three Chosen, and there are only four heritages.

I assume that this means that multiple players are likely to end up playing the same role. Assuming that is accurate, I wanted to ask about how this works in practice, e.g.

If you have two quartermasters is this going to effect game balance? and do the two different quartermasters feel different to each other?

Or alternatively, does someone sit out that part of the game? (Which seems like it would suck) Or the last alternative I can see, is that you have the rookie playing with the chosen. Which sounds worryingly like playing bob the ice cream truck driver with Captain Marvel.