ASP.NET Build Error : The type exists in both dlls
<p>While building my project, I got the below error message.</p>

<blockquote>
  <p>The type 'tracker_ascx' exists in both
  'AppData\Local\Temp\190\Temporary ASP.NET
  Files\root\web_tracker.ascx.7a9a6bd4.fnv2mhdj.dll' and
  'AppData\Local\Temp\190\Temporary ASP.NET
  Files\root\web_tracker.ascx.7a9a6bd4.pxdl7dxj.dll'.</p>
</blockquote>

<p>The application runs in <code>.NET Framework 4.0</code></p>