Assign Users to Project Role handles case sensitivity in username wrong - association that cannot be deleted

When user is assigned to project in some role and user types username himself, this leads undeletable association.

If we have user with username test and we associate her by typing test to "Add user(s) to project role" text box association is created and can be deleted. But if I type Test I can create an association that cannot be deleted - nothing happens if I try to delete user.

SQL Server itself is configured to case-insensitivity and query to projectroleactor table returns role mappings in a form they were typed (some as 'test' and some as 'Test').