title: How do I identify OpenID username when identifier has no username in it?
body: <p>I am trying to implement openID on my site and read through like <a href="http://www.plaxo.com/api/openid_recipe" rel="nofollow">Plaxo</a> and questions on SO. I am currently able to authenticate my users using the libraries. But I notice that some providers like </p>
  
  <ul>
  <li>Google : <a href="https://www.google.com/accounts/o8/id" rel="nofollow">https://www.google.com/accounts/o8/id</a></li>
  <li>Yahoo  : <a href="https://me.yahoo.com" rel="nofollow">https://me.yahoo.com</a></li>
  </ul>
  
  <p>I am trying to implement a system similar to Plaxo, where I will have  many-to-one relationship for account. But how do I distinguish users using openID urls like the above? I see even SO having google and google profile seperately. So, how do they identify the user in the case where user don't provide his username or I should say unique openID?</p>