An authorization hold (or pre-authorization) is a temporary reservation of funds or credit by your card issuer to check that your payment method can cover your order.
The hold isn't a completed charge or an extra payment. It temporarily reduces your available balance or credit while the payment is being processed.
Once the order is completed, the charge is finalized. If your order isn't completed, the hold is released, but it may take a few days for your card issuer to make the funds available again.
If the hold is still there after several days, contact your bank or card issuer for help.