For Single Sign-On authentication, users who have not already been added to the system may generate a new Applicant account prior to be used as a Reference of Reviewer. Once the Applicant role is added to an account, it cannot be removed. 

Instruct the References or Reviewer's to select the correct role by selecting their email address in the top right and using the drop down options available. 

To prevent this from happening please see documentation about the Remote Identity API.