Does anyone know if the Barnes and Noble coupons sent through email have a unique one-time code, or can they be used more than once? I was sent a 30% off coupon two days ago, so I printed it-once. I always print the coupons they send me just once. Today, however, I got another email with the same coupon and the same code. I always assumed each was a unique code, but now I'm wondering if I can print the same coupon for my daughter to use. Anyone have any experience with this?