title: LINQ: Distinct values
body: <p>I have the following item set from an XML:</p>
  
  <pre><code>id           category
  
  5            1
  5            3
  5            4
  5            3
  5            3
  </code></pre>
  
  <p>I need a distinct list of these items:</p>
  
  <pre><code>5            1
  5            3
  5            4
  </code></pre>
  
  <p>How can I distinct for Category AND Id too in LINQ?</p>