title: Multiple Facebook IDs for the same user
body: <p>i'm crawling user comments and its user ids in public links to build a graph, and i noticed some users have more than one ID. For example, this user have two different IDs: 100000571429851 and 993673107328394.</p>
  
  <p>I'm not using different aps to get the user ids (someone told me user IDs changes between different apps).</p>
  
  <p>Any ideas about how i can get a really unique ID for each user?</p>