You may have heard that you can only use one coupon per item. This is true for some coupons, not true for others. Knowing how manufacture coupons and store coupons are different is key to stacking and doubling coupons. You may only use 1 MC per item, and 1 SC per item. But
Stacking coupons is using a manufacture coupon and a store coupon together to get a fantastic price. Almost every store who prints their own coupons allows this!
Doubling coupons is taking advantage of certain stores promotion to double the value of whatever manufacture coupon you bring in. (In western WA, Albertsons, Summit Trading CO, and Kmart.)