title: ISharedPreferences deletes duplicates when inserted
body: <p>For example, I have a simple List:</p>
  
  <pre><code>List&lt;string&gt; s = new List&lt;string&gt;();
  s.Add("eg1");
  s.Add("eg2");
  s.Add("eg3");
  s.Add("eg1");
  </code></pre>
  
  <p>Lets say I want to now insert in into my <strong>ISharedPreferences editor</strong> called <strong>editor</strong>:</p>
  
  <pre><code>editor.PutStringSet("eg", s);
  </code></pre>
  
  <p>Now, I want to access this list by doing this:</p>
  
  <pre><code>ICollection&lt;string&gt; eg= prefs.GetStringSet("eg", (ICollection&lt;string&gt;)new HashSet&lt;string&gt;());
  List&lt;string&gt; s2 = eg.ToList&lt;string&gt;();
  </code></pre>
  
  <p>The problem is that I have duplicates like "eg1" in my list but the editor deletes them.</p>
  
  <p>My question is how can I prevent the editor from deleting duplicates in my list?</p>