If you claimed the Recovery Rebate credit on your 2020 tax return because you did not receive the second stimulus then subsequently receive your second stimulus payment by mail or direct deposit, I advise that you should wait to receive your refund before taking any action.
It is likely that the IRS will cross-check with their records and adjust your refund. If they do, all is fine and nothing needs to be done. If they do not adjust your refund, then you should amend your return and correct the Recovery rebate credit. With your amended return, you will enclose a check equal to the overpayment.