error when adding a default page to web.config
<p>I have 1 webpage with a SQL connection. When I run on localhost on Windows 7, this error occurs. </p>

<blockquote>
  <p>HTTP Error 500.19 - Internal Server Error</p>
  
  <p>The requested page cannot be accessed because the related configuration data for the page is invalid.</p>
  
  <p>Config Error Cannot add duplicate collection entry of type 'add' with unique key attribute 'value' set to 'default.aspx'  </p>
  
  <p>Config File \?\D:\SIPLWEB\WebSite\web.config </p>
</blockquote>

<pre><code> 120:             &lt;files&gt;
 121:                 &lt;add value="default.aspx" /&gt;
 122:             &lt;/files&gt;
</code></pre>
