title: "username" parameter coming back with more than I gave it!
body: <p>This is really weird - I've got a MVC app running, including a <code>Login</code> method in my <code>ServicesController</code> class:</p>
  
  <pre><code>public ActionResult Login() {
    var p = Request.Params;
    var userName = p["username"];
    var password = p["password"];
    // etc...
  }
  </code></pre>
  
  <p>The weird thing is that when I call the service with the request:</p>
  
  <pre><code>/services/login?username=myusername&amp;password=password
  </code></pre>
  
  <p>I get into the code and find that <code>userName</code> is "anotherusername,myusername".  Depending on what browser I'm using, I get different values in place of "anotherusername", which I recognize from some other apps I'm developing.  So is "username" some kind of reserved word that one shouldn't use as a parameter name?  What other reserved words are there that cannot be used safely as parameters?</p>