We are linking buyers with to our affiliates using coupons single use per customer.
These coupons, in addition to the function of the affiliate entailment, also provide a discount to the buyer.
We have a problem: when a customer uses a coupon is linked perfectly affiliate and the affiliate receives commissions that buyer, always. But the buyer can use the coupon for another affiliate to regain a new discount, but not be linked to that affiliate.
How can we avoid it automatically, a buyer can use more than one coupon affiliate, to prevent receive a new discount?