Pre Payment?

[Martijn Heuts]

  Hello,
I had to unpost an invoice as it was posted as paid in full but it was not (we applied discount instead of having an open balance). Now that I have the discount reduced and the payment posted it shows when I click on 'Pay Invoice':
6/14/2017   Invoice              62.006/30/2017   Pre-Payment                   62.00
The date the invoice was created was 6/14The date the invoice was paid 50% was 6/14The date that I got insurance money for this invoice was 6/22 (this is when the invoice was entered paid in full after discount)On 6/30 it was unposted, discount was reduced to reflect the open balance, and payment for remaining balance was posted again.The post date was set to 6/14 and the due date set to 6/30.
Can someone tell me why it shows pre-payment and how to fix it?
Thanks for all your help. Have a blessed 4th of July!!
Martijn