title: Using session_start twice
body: <p>I have a pretty dumb question (I believe): </p>
  
  <p>What would happen, if I were to start 2 sessions, calling <code>session_start()</code> twice? For example, I have a class <code>User</code>, where I start user's session, and a class <code>Error</code>, in which I start another session, so I can store errors and notifications in them and pass them to other pages.</p>
  
  <p>Could I run into a problem, and is this efficient?</p>