Can a player run 2 characters in the same campaign on DDB?

I'm running a campaign and would like one of my players to add another character to play. He already has a character assigned to the campaign. He created the 2nd character but it's showing as "unclaimed'. If he claims the character, will his first character become unclaimed and unplayable? Does anyone know?

You can share the join link again and it will function the exact same way. I have several campaigns where I have two characters in them.

Quote from MetalSentinel >>

I'm running a campaign and would like one of my players to add another character to play. He already has a character assigned to the campaign. He created the 2nd character but it's showing as "unclaimed'. If he claims the character, will his first character become unclaimed and unplayable? Does anyone know?

No. This happened in the campaign I ran when one player had to take over the character of a departing player. You can have multiple characters  controlled by a single player, assuming the player isn't at the maximum number of characters they can control when they try and take over one.

in most of my campaigns almost every player has multiple characters added, not because they’re playing multiples but because you can only share material if a character is created in a shared campaign. Players can either claim unassigned characters or just keep using the join link to create new ones 

We are currently playing 3 different groups in the same campaign at different points in the same story.  It's maddening trying to keep straight which character knows what, but we are making it work.  The Party Inventory took a bit of organizing though.

Quote from MetalSentinel >>

I'm running a campaign and would like one of my players to add another character to play. He already has a character assigned to the campaign. He created the 2nd character but it's showing as "unclaimed'. If he claims the character, will his first character become unclaimed and unplayable? Does anyone know?

 I took over a character in game. If the character is already claimed, they can unclaim. Then the player that will play it claims it. 

If the player rolls up 2 characters on his account, and adds them to the campaign, they both would be played by same player.

I never tested logging in with 2 separate beyond accounts at same time. So can’t verify that.

Yes.