title: asp.net context An item with the same key has already been added
body: <p>I´m facing a problem when I try to run the following line:</p>
  
  <pre><code>public class HomeController : Controller
  {
      private EspEntities _context = new EspEntities();
  }
  </code></pre>
  
  <p>I get a message:  </p>
  
  <blockquote>
    <p>An item with the same key has already been added.</p>
  </blockquote>
  
  <p>I've tried to replace the Edmx file, but I can´t figure out why this is happening. Does anyone know how to fix this?</p>