The Issue : Visual Studio throws the following compile time error on a project that includes UI controls (either WinForms or ASP.NET controls).

The item was specified more than once in the resources parameter. Duplicate items are not supported by the “Resources” .

Solution: Simply open up the .csproj file – and look for the occurence of the particular resource  (item). This resource item name appears in the exact compiler error. In my case, the resource name was SyncfusionVirtualGrid – and my .csproj contained an entry such as:

  <EmbeddedResource Include="SyncfusionVirtualGrid.resx">

      <DependentUpon>SyncfusionVirtualGrid.cs</DependentUpon>

    </EmbeddedResource>

  

Remove this entry from the .csproj file (Alternatively, you can just right click on the .resx file – and delete it from there).

This should resolve the compilation error.