How to have one of a card in your main deck and another in your sideboard?

{"ops":[{"insert":"Definitely not being dumb-- if it's not intuitive for you, it says more about our design!\n\nYou can do this by hitting the blue arrow to the right of any card that you've pulled up in a search. From the new menu that comes up, adjust the \"Add to this category\" dropdown menu to read \"Sideboard\" or whichever the other category you want the card in. Adding from here should allow you to have copies of the same card in different categories. \n"}]}