Filed our 2020 return. Filed an amended return an hour later. Original we get money back. Amended we owe. Is the difference billed to us?

We filed our 2020 return in April this year showing a refund to us of $2200. We then realized we forgot to include Social Security earnings and filed an amended return an hour later which showed we now owed the IRS $600. The IRS has already direct deposited the $2200 into our bank account. The QUESTIONS: Since we now owe the IRS $1600 what is the correct procedure to pay it? Will we be billed or do we simply send the IRS a check? The concern here is if we send a check will the IRS reconcile it with the two filings? Or will the IRS simply debit the amount owed from our bank? Thanks in advance as it's our first ever amended return.