I hoped it was can get one but with clause.
People can sell their card. and get another. But the selling of the card would reset and those missions would need to be done again. to the level of he card sold.
Somehow adding a % to the amount of missions needing to be completed.
Just a thought, Maybe not wrote too clearly.
Interesting idea but it defeats the object of making them very hard to get by only allowing one per player. It's something we have never done before and adds a different element to the game.
Might be an idea you can use or upgrade for something else later :)