title: C# FileInfo - Find duplicate Files
body: <p>I have a <code>FileInfo</code> array with ~200.000 File Entries. I need to find all files which have the same filename. I need as result from every duplicate file the directory name and filename because I want to rename them afterwards.</p>
  
  <p>What I've tried already:</p>
  
  <ul>
  <li>Comparing each Entry with the whole List with 2 For "loops" // Bad Idea, this would need hours or even days ^^</li>
  <li>Try to use Linq Sorting // Because i not used Linq before i have hardship to write the correct Statement, maybe someone can help me :)</li>
  </ul>