Ala. Code § 5-19-9
When the buyer is indebted to a particular seller for two or more consumer credit sales of goods and the goods which were the subject of two or more sales secure the buyer's total debt to the seller, the security shall be discharged by applying the buyer's payments as they are received by the seller or the seller's assignee to the portions of the debt in the order in which they were incurred. To the extent that debts are paid according to the preceding sentence, security interests in items of property terminate as the debt originally incurred with respect to each item is paid. Payments received by the seller upon a revolving charge account are deemed, for the purpose of determining the amount of the debt secured by the various security interests, to have been applied first to the payment of finance charges in the order of their entry to the account and then to the payment of debts in the order in which the entries to the account showing the debts were made. If the debts consolidated arose from two or more consumer sales made on the same day, payments received by the seller are deemed, for the purpose of determining the amount of the debt secured by the various security interests, to have been applied first to the payment of the smallest debt. This section shall not apply to two or more consumer credit sales made by the same seller to the same buyer when the debts have been assigned to different and unrelated persons for value and the assignment was bona fide and not for the purpose of violating this section.
Ala. Code § 5-19-9 (1975)