Switching from local user database to SAML login

I am currently running Jenkins 2.318 and testing SAML logins. It works, but noticed that if everything about the user is not the same (display name, case, etc), it will create a duplicate user. Is there a sure way to make sure that when I go live, the SAML login will take over the current local user? Also, is there any way to get the group attribute to pass correctly? I can’t seem to get that to work. For the record, I am using JumpCloud as the SSO provider.