User can login with email or user and duplicate user

[Víctor Pardo]

We have SSO with Azure AD. The user login with is email and was redirect to Microsoft authentication. This logon the user correctly and can open case without problem.

When the user logon directily with user instead of email, atlassian permit access, open tickets, but duplicate the user and don't assign "customer id" to the ticket.

Any suggestion to limit login with email or deny login with user?

Thanks in advance.

[Richard White _TechTime_]

Its not 100% clear from your question:

> When the user logon directily with user

What does this exactly mean? Are they entering email / password in Atlassian login page directly? Atlassian accounts are unique by email as far as I am aware, so if they are entering a different email address it will use the account for the second email. 

It might be worth checking what exactly is the email address that Atlassian is using for the user id. From https://learn.microsoft.com/en-us/entra/identity/saas-apps/atlassian-cloud-tutorial: 

> Atlassian Cloud expects the nameidentifier (Unique User Identifier) to be mapped to the user's email (user.email). Edit the Source attribute and change it to user.mail. Save the changes to the claim.

However if a different attribute is used, or there are other email aliases which the user is using another account might be created.