Can you print out a few of the same coupon and use them even though they all have the same serial number? Or will it come up at the register when you try to use it again?

You can print out and use the same coupon over and over--one per customer per day for the length of validity-- the barcode doesn't change for ANY customer.

If you're short on time, bring a child/hubby/bf/girlfriend and give them some money, a coupon, the item you want, and tell them to get in line behind you.