What constitutes an "incomplete payment" form?

We have several forms that are designated "incomplete payment." There is some confusion as to what constitutes an "incomplete payment" as it contains forms whose payments appear to have been made in full.

A second question is why are there multiple forms by a single applicant?  

Thank you! 

An incomplete payment means that the user did not process the payment while on Paypal side, please read this articles that explains further what constitutes an incomplete payment:

https://www.jotform.com/help/272-Paypal-Incomplete-Payments-FAQ 

I would recommend you to enable Paypal IPN. Instant Payment Notification is a POST message sent by Paypal (for regular merchant accounts) whenever a transaction is completed on their side: https://www.jotform.com/help/276-How-to-Enable-IPN-for-Paypal 

Note: Completing a submissions will NOT process any payment as there was no payment information to begin with. The system will simply treat this as a regular submission so it can be included on form reports, and that email alerts can be fired off as usual: https://www.jotform.com/help/135-How-to-view-incomplete-payments 

On regards of preventing users making multiple submissions, you may set unique submissions on your form, please check this guide to learn how to enable this feature: https://www.jotform.com/help/64-How-to-Set-Unique-Submissions-on-a-Form 

Let us know if you need more help.