Wondering

The other day when I was at the grocery store, they had some coupons for a product available and with the coupon, I was able to get the product for free.  The coupon came out of a machine that would dispense one at a time.  I went ahead and got two of the coupons, but I wondered if there is proper etiquette for this circumstance.  I didn't want to grab all the coupons and thus prevent someone else from getting the same deal, but I wondered how many coupons would be acceptable to take each time.