title: Devise - how to change setting so that email addresses don't need to be unique
body: <p>I set up Devise to log in with a username instead of email address because a significant number of our users share the same email address with their spouse. It is a unique market that we serve. But each spouse needs separate accounts to record personality instrument results.</p>
  
  <p>The database no longer requires a unique email address so it will accept the same email addy for two accounts. However, Devise is still requiring a unique email address for each account. Is there a setting or a work around that i can use to change this?</p>