Duplicate Certificate Warning

Can we get a warning prior to issuing certificates when one or more enrolments in the selection already have a certificate issued?

This is a major issue for partners who are spending actual money when performing this action so a simple warning would prevent them from doubling up and causing a whole range of finance and administration problems.

I understand there's a little icon showing when one is already issued but this has proven to not be effective.

A user role setting to remove the option to issue multiple certificates entirely would be even better, but presumably more complex.