The item \xxx\yyy.cs“ was specified more than once

Question

I have following error :

 

The item \xxx\yyy.cs“ was specified more than once in the ”Sources“ parameter. Duplicate items are not supported by the ”Sources" parameter

 

this is an mvc web application. I have read many blogs and articles which are relevant to this but does not find any solution. i have checked in .csproj and does not find any duplicate entries for file in .csproj file.