Doesn't it depend on which class is duplicated? It would be subefficient for a party to have two characters that are good at picking locks and detecting traps. A waste of investment. I will admit I am not immune to such considerations. I wouldn't call it minmaxing, it is about having a sensible, versatile party composition. But I would not shy away from having two barbarians in the party, being partial to that class myself. If one barbarian is good at killing stuff, two are twice as good. And it will be interesting to see who, between Karlach and my character, is the most barbaric.
