title: Query a list for only duplicates
body: <p>I have a List of type string in a .NET 3.5 project. The list has thousands of strings in it, but for the sake of brevity we're going to say that it just has 5 strings in it.</p>
  
  <pre><code>List&lt;string&gt; lstStr = new List&lt;string&gt;() {
              "Apple", "Banana", "Coconut", "Coconut", "Orange"};
  </code></pre>
  
  <p>Assume that the list is sorted (as you can tell above). What I need is a LINQ query that will remove all strings that are <strong>not</strong> duplicates. So the result would leave me with a list that only contains the two "Coconut" strings. </p>
  
  <p>Is this possible to do with a LINQ query? If it is not then I'll have to resort to some complex for loops, which I can do, but I didn't want to unless I had to.</p>