Create User When Identity Exists?

Good day all.  I am running into a problem when trying to create a User.  I have an Identity that is used during Lifecycle Released state for documents.  I would like this Identity to send an e-mail to a specific account.  I figured that I would create a User to add the e-mail to, but when I create the User I receive a message stating that I can't because the Identity already exists.  How can I fix this issue?  Also, how can I associate the two?  Thank you for the help.