Multiple Discount Codes Per Purchase
Since Easy Digital Downloads version 1.7 and later, there is an option to allow customers to redeem multiple discount codes per purchase. This means that instead of just using one discount, customers can stack discounts and save more per purchase. This is great for special promotions.
To enable multiple discounts, go to Downloads > Settings > Misc (tab) > Checkout Settings (section) and check the box that says "Multiple Discounts":
Customers will now be able to enter multiple discount codes on checkout. When a customer has redeemed multiple codes, they will be displayed like this: