Incorrect calculation of financial data.

Pre-conditions:
Here are the minimal setup required for reproducing this bug.

• create a fee/fine owner
• create a manual charge for this owner
• create a payment method

Steps to reproduce:

• go to users app and click on some active user
• open fees/fines section and click on a "Create fee/fine" button
• fill the form based on setup from the pre-conditions
• click a "Charge only" button
• select just created item and open a details page
• click on "Pay" button and enter Payment amount less than Selected amount
• chose "Payment method" and click "Pay"
• REPEAT two previous steps without reloading the page.
• reload the page.

Expected result:
"Pay" button will be disabled when payed amount will be more than billed amount.

Actual result:
We still have Remaining amount more that 0, but we have paid more than Billed amount.