You will not be charged twice.
Two pending charges will show on an online bank statement if your first attempt to pay fails and you correct your credit card information and submit a second time. Whenever a payment is submitted, the charge is automatically pre-authorized by the credit card company even when the card is declined by the credit card company. This charge shows up as a "pending" charge on your bank account. If our system accepts that payment, we send that charge through and it will post to your account. If our system declines your payment, then that charge will not be fully processed and the pending charge will go away within a few business days.
If you have a double charge because you clicked multiple times on the Pay Now button on the Payments screen while the credit card was being processed, any extra charge will be taken off automatically. There will be two or more pending charges on your online bank account, but after a few business days the extra pending charges will go away and only one transaction will be processed.