I have Quickbooks Online. I invoiced a customer and he paid via Quickbooks online payment, and then he sent a check as well--not realizing he paid the same invoice twice. The check was deposited into the bank before realizing that it was a double payment. I need to:

1) Record the deposit into my bank so that I can reconcile, and

2) Record the credit in the customer's account so that he can use the credit for future invoices.

I don't want to issue a refund, and there is no open invoice at this time to apply the payment to. I haven't come across any scenarios exactly like mine. Can someone please walk me through the steps and explain the purpose of each?

Thanks in advance!