Why does each order form have a few incomplete payments even though one went through to paypal?

Each order form has a few "payment incomplete" notifications. I've checked one and the payment did go through so far as I can tell from paypal. Why would this happen? Is everything ok with their order? 

I believe that you are actually referring to Incomplete Payments and you can refer to this guide here https://www.jotform.com/help/564-how-to-view-incomplete-payments-of-your-payment-forms/ to learn more.

Which submission went through? If it ended up as an incomplete payment at first but, was finished later then it is possible the customer went back to finish it.