If I claimed the Recovery Rebate Credit because I didn’t get the second stimulus, but the IRS mailed it later, how do I pay back the extra $600?

My direct deposit information changed before the second stimulus went out. I thought the IRS wasn’t reissuing payments so I claimed the Recovery Rebate Credit. I checked again this week and the IRS is mailing a check. I don’t want to double-dip, but I already filed my return. How do I pay back the $600? Do I cancel or void the check?  What should I do?