This is actually answered in the question after the one that asks what happens when characters die, so you might have missed it:

"Characters can also be dropped via death, but only if they have already contributed significantly to the game, have mod permission, and the death is plotted/threaded out. If a character dies in game they cannot be apped again."

The situation you described couldn't happen, since players require mod permission to play out a death plot, and to do that they need to have contributed "significantly" which essentially just means that they need to have been a big part of the game and played out a meaningful arc. And anybody who does that deserves to be the only one to play that character in a game, in my opinion.

Deaths are meant to be a very big deal, and they would lose a lot of their meaning if the character could just be reapped by another person later. When someone dies in Lost Carnival, plot business aside, they are never coming back. They're gone in the game setting, and they'll be gone in their canon setting too, as far as the metaplot is concerned.