Here is a new Healthy Ideas booklet that I found at my Giant store:
It has lots of great recipes and coupons inside. Most of the coupons are Giant store coupons and can only be used in that store. They look like this - note that the UPC number starts with a 2:
Giant store coupons can be "stacked" - or combined with - manufacturer's coupons!
The booklet has a few manufacturer's coupons inside. Even though they have the Giant store logo on them, they can be used anywhere. Note that the UPC number begins with a 9:
Manufacturer's coupons that begin with a 9 will not double at the register. Manufacturer's coupons that begin with a 5 will double at the register, even if they say "do not double" on them. It is the job of the cashier to catch them and ensure that they don't double, but most cashiers don't bother.
Doubling coupons is an expense borne by the store to encourage you to shop there, so I have never understood why some manufacturers put "do not double" on their coupons, since it does not cost them anything extra anyway.