Duplicate transactions are very rare, and we work hard to avoid them. The best indicator that you have a duplicate transaction is if you received more than one receipt email with different transaction IDs.
Multiple charges appearing on your online banking statement immediately after the transaction doesn't necessarily mean there is a duplicate transaction. If you had to submit the payment form multiple times for any errors, this may cause multiple transactions to appear for 2-3 business days until the bank reconciles the transactions.
If you have any questions about duplicate transactions, contact customer service at email@example.com or 877-327-1226.