You do not amend for that. That is a common issue and the IRS will cross check and recalculate your refund to take off the "doubled" amount of stimulus that ended up on your tax return. It might delay your refund while they do that.
If you file your taxes and claimed the Recovery Rebate Credit (RRC) and then suddenly receive your stimulus money.
Don’t rush into amending your tax return. It is our understanding the IRS will be cross-checking their stimulus payment records with the RRC claimed on returns and adjust refunds as needed.
It’s best to wait until you receive your refund before taking action. The IRS will most likely make the adjustment for you so you are not compensated twice.