It seems Prestashop's awocoupon version allows for one automatic and one typed in coupons, even though multiple coupons is set to NO.
In joomla, there seems to exist an {exclusive} tag that prevents this. Is there such a possibility in Prestashop ?
Let me add that if it is the expected behavior, I don't think it's a good one. If you say Multiple Coupons : No, it means No...