How do I deal with people choosing the same class? Can people do it? I have one player who doesn’t think so and is really unhappy about it and is telling me I have to figure out why they should care to stay with the party, and I don’t know how to handle them. What do I do?
I am at the point where I’m wondering if I have terribly broken some unspoken rule of DMing, and need expert perspective.
The whole situation
Here's the situation. I am setting up an in-person roleplaying group. I already have the basic first encounters prepared for Session 1/0 depending on how you like to call it. I already made every character out there and sat with each player while doing so, because I like to keep track of the characters, put notes about them and overall, well, I tend to playtest combats to make sure I didn't just toss something that will TPK people (I also take in account that I don't account for their possible actions, thus I playtest many times and make sure that the encounter is won with relative ease because I know I can make it harder on them if need be.)
The thing is, two players wanted to play blood hunters (a homebrew class by Matt Mercer), and two players wanted to play rogues, when I was talking to them about the ideas they had, before we solidified anything, I did note that every one of them wanted to go do something different, one of the rogues is an exile who has lived hardships and is now hiding their identity because they are an albino character, a sign of a bad omen, and his father, a noble, wants them dead.
The other rogue is a swashbuckler, a person who has centered on duels his entire life and seeks for power. You get the deal and idea, even in the same class, I accounted that every one of them had something special and different to them, I gave each one a different custom backstory, etc.
One of the blood hunters was super excited to play one, they never played one and they loved the class. But when they realised that they weren't the only blood hunter, they wanted to switch classes, which I allowed, but here's the thing. The guy is now throwing me the "Sure..." type of text messages, you know, the typical "I am doing this cause am forced to" deal. When I asked them that if they were alright, they just say yes, and when I told them, "Look, having the same class as someone else in my eyes is not the important thing, the class doesn't define your character, what they lived through, their experiences, and the like, does," they basically told me that "You better have a good reason for my char to stick to the party." (Because their character didn't like other blood hunters, something which I accounted for, and the second player is seeking for the same person he hates because they were part of a BH order that disappeared, yada yada.)
I always accounted that having reasons to stick to a party is a shared responsibility, after all, the players are in control of their characters, and it was partially a DM's responsibility to merely make sure the bond is there, there are reasons, and the bond with others can strengthen.
I honestly just want to know how to deal with it.
Should I not allow people to choose the same class? Should I let people who complain to me like this leave?
I have enough players to start anyway; I've just never dealt with it as a DM, and wanted to know if the player is right and I’ve done something wrong.