Able to enter duplicate Payment Method for Fee/Fine Owner

Overview: 

We are now able to enter a duplicate payment method for a fee/fine owner.   Previously this was not allowed.

Steps to Reproduce:

1. Log into https://bugfest-iris.folio.ebsco.com/ as admin user
2. Go to Settings>Users>Fee/fine: Payment methods
3. Select a Fee/Fine Owner
4. Enter a Payment Method that already exists for the Fee/Fine Owners

Expected Results:

Not allowed to add duplicate Payment Method for a given Fee/Fine Owner.  On Honeysuckle BugFest instance this error message appears: Payment method already exists

Actual Results:

Able to add a duplicate Payment Method for a given Fee/Fine Owner.