It is definitely not realistic to have multiple characters of the same type at once, but I have no problem with it (nor, as far as I know, does the majority of the playerbase). It's one of those things that is just a part of Renegade and Renegade X, and I think that Renegade X should stay mostly true to Renegade in that respect. There are some changes (such as the replacement of cheap Sydney with Mcfarland), but they are minimal.
As to Commando units, there are a few issues I can think of. The first is that it simply would be a large change to game balance and overall strategy, at a rather late phase in the development of Renegade X, and at a time when such changes really are not necessary (in my opinion, at the very least). Secondly, the limit of one per team - it works well in an RTS, with one person controlling a whole team, but in an FPS, it is very exclusionary, and players may be frustrated to find that the slot for the Commando unit they want to play is always full when they go to buy it.
In short, the current system is part of the Renegade heritage that I believe we should uphold, and I do not see such major game balance and strategy changes as being necessary at this point of the game's development.
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