Candidate Submitted Tier 2 Application Without Email Address

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We are using TBE.  We sent a candidate an invite to complete the Tier 2 application.  When they completed and submitted the application, a new candidate profile was created in Taleo with a blank email address.  This candidate now has two profiles.  We have not had this happen before and not sure why this happened as the email address is a required field.  Has anyone else experienced this?