Problem with LDAP User Name Changes in SpiraTest

Here is the scenario I'm have trouble with in our environment, with names changed:

I have an LDAP-managed user whose name changed from Mara Jade to Mara Corning.

As expected this broke the LDAP linkage in Spira, as this also changed her DN.  Upon relinking the account, however, I am unable to set the Spira login username to reflect the change; if I try to manually enter "MCorning" as a username, I get the error "The entered user-name is already in use, please choose another!", however if I search for this username within Spira, it shows no results.

Changing her username to "MaCorning" allows her to login with her LDAP password without issue.

Has anyone else run into this?