This is most notable with books for the Bookworm transformation: each character needs 3 different books. This allows each bomb to cover double the area by positioning the characters in different locations. As a result, if the player can handle the increased difficulty from these optional chapter paths, item rooms in Downpour, Mines, and Mausoleum (including their alternative variants) have double their normal value.
Curse Room door damage will only be applied to the character that moves through the door.
If one character passes through a door, both characters move to the next room.