A debtor knows about an assignment of debt but pays the assignor instead of paying the assignee will still be in debt to the assignee

A bank provided credit to a company against a charge on its assets. The company engaged in a transaction and issued invoices explicitly stating that payment is to be paid directly to the bank, and not to the company, but the counterparty paid the funds to the company and not to the bank.
The Court held that the counterparty who paid the funds to the company and not to the bank personally owes the funds to the bank. If a payment order indicates that it is irrevocable, this indicates an assignment of rights, and that the right to receive the payment was assigned to a third party. Assignment of rights consists of two elements: A contractual element in the form of creditors' subrogation, and a property element, in the form of transfer of ownership in the original creditor’s rights. Subrogation means that the original creditor ceases to be the debtor's creditor, and the third party becomes the creditor for all intents and purposes. In general, in the absence of any other agreement, the result of such assignment is that if the debt is not repaid, the third party is entitled to collect the payment from both the debtor and the assignor. Here, the transaction invoices specifically stated that the payment is to be made to the bank. Thus, when the counterparty paid tto the company and not the bank, , a personal obligation to the bank was created.