title: Rename List item when there is the same string multiple time
body: <p>I have <code>List</code> of names like:</p>
  
  <pre><code>var list = new List&lt;string&gt; {"Allan", "Michael", "Jhon", "Smith", "George", "Jhon"};
  </code></pre>
  
  <p>and a combobox which itemssource is my list. As you can see in the list there is Jhon 2 times, what I want is when I put those name into combobox add "2" to second Jhon. I mean when I open the combobox names in it shoud look like: </p>
  
  <pre><code>Allan
  Michael
  Jhon
  Smith
  George
  Jhon2
  </code></pre>
  
  <p>I have tired linq to do that but I'm quite new to c#/linq. Could someone show me simple way to do that?</p>