Just mark the appropriate box at the top of the passport application. There is no risk. They will give you one if they have the supplies. Some agencies have passport card facilities on site, so if that's the case, you'll get that at the same time too. If they don't, they will send it by post at a later date. You don't need both the book and card for your trip in 2 weeks. You just need one.
*** El Cafe ***
N400 - NYC (Brooklyn)
March 12 2010: Sent
April 7 2010: FP done- walk-in
August 3 2010: ID decision not made
December 12 2010: Lawsuit filed under 8 USC 1447(b)
March 31 2011: 31 Oath date
April 1 2011: Passport applied, picked up!