title: ASP.Net/web.config - "The entry 'x' has already been entered"?
body: <p>In ASP.Net when I see the error message "<strong>The entry 'x' has already been entered</strong>" I think that means a name (in this case 'x') is defined twice in <strong>Web.Config</strong>. </p>
  
  <p>Is that a reasonable summary of what causes that error or are there other ways it could be generated ?</p>
  
  <p>The 'x' in question doesn't appear twice in the web.config - any ideas of what else could be causing this error ?</p>