title: Message IDs on duplicate messages
body: <p>According to the documentation for SQS (emphasis mine): </p>
  
  <blockquote>
    <p>Amazon SQS stores copies of your messages on multiple servers for redundancy and high availability. On rare occasions, one of the servers storing a copy of a message might be unavailable when you receive or delete the message. If that occurs, the copy of the message will not be deleted on that unavailable server, and <strong>you might get that message copy again when you receive messages</strong>. Because of this, you must design your application to be idempotent (i.e., it must not be adversely affected if it processes the same message more than once).</p>
  </blockquote>
  
  <p>Are these duplicate messages guaranteed to have the same (SQS) message ID?</p>