A duplicate transaction error on a payment form

Our customers are having difficulty when they try to register a second child using the same information as the first child. It appears that these are

Thank you for contacting us.

Are they getting the following error on your Authorize.Net payment form?

Error 11: A duplicate transaction has been submitted.

If this is the case, you might consider suggesting your customers wait two minutes before submitting a new form entry (to bypass Authorize.Net duplicate transaction time frame), or use another credit card for the second entry.

There is Duplicate Transaction tracking mechanism on Authorize.Net, it has two minutes time frame by default. You can find more information in their documentation:

Error 11: A duplicate transaction has been submitted.

Please feel free to contact us if you need any further assistance.