title: System.Web.Mvc.ModelClientValidationRule' exists in both locations error
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/9471263/mvc-4-beta-side-by-side-installation-error">MVC 4 Beta side by side installation error</a>  </p>
  </blockquote>
  
  
  
  <p>I get this error</p>
  
  <blockquote>
    <p>Error 1    The type 'System.Web.Mvc.ModelClientValidationRule' exists in
    both  'c:\Program Files (x86)\Microsoft ASP.NET\ASP.NET Web
    Pages\v2.0\Assemblies\System.Web.WebPages.dll'  and 'c:\Program Files
    (x86)\Microsoft ASP.NET\ASP.NET MVC 3\Assemblies\System.Web.Mvc.dll'</p>
  </blockquote>
  
  <p>After I have changed <code>Copy Local</code> to <strong>false</strong> for some ASP .NET MVC3 DLLs</p>
  
  <p>How can I stop this error from occurring?</p>