title: Error: The type exists in both directories
body: <p>In a MVC2 project I moved a file from App_code to Content folder and compiled it. Then move it back again to App_Code and then changed its Build Action to "Compile". Now I get this error and I don't know how to fix this to make my program work again:</p>
  
  <blockquote>
    <p>CS0433: The type 'Helper' exists in
    both
    'c:\Users...\AppData\Local\Temp\Temporary
    ASP.NET
    Files\root\b00d4b7d\b2553f9c\App_Code.zowyklar.dll'
    and
    'c:\Users...\AppData\Local\Temp\Temporary
    ASP.NET
    Files\root\b00d4b7d\b2553f9c\assembly\dl3\5c6d3537\19f85663_cde9cb01\MyProject.DLL'</p>
  </blockquote>
  
  <p>Cleaning and Rebuilding doesn't solve the problem.</p>