You probably backed the previous campaign to produce all formats of the book that was unsuccessful in meeting the goal amount. When a project doesn't meet the goal, Kickstarter will not charge you. This is an entirely new campaign that is focused on producing the printed copies. Your donation is totally valid here! Feel free to donate as much as you would like to help us (me and the other backers) reach our goal. :)
Don't see the answer to your question? Ask the project creator directly.