Question: I recently installed Visual Studio 2010 and copied and converted an old VS2005 solution to VS2010

When I edit this solution, if I try to change a control's .image property, VS2010 creates a message box telling me that "An item with the same key has already been added", and won't let me browse for an image.

I can add images for any other solution, even others ported from VS2005, but not this one. Any idea what I'm doing wrong?

Answer: 
I worked this out thanks to a search. The solution is to never create a .resx file with the name "Resources.resx" because it conflicts with the "Resources.resx" files that can be automatically created in the project's properties dialog.

Once I renamed Resources.resx to Icons.resx, I was able to change the image property for anything in the solution.
\*in vs2015 if you get "An item with the same key has already been added" like image bellowm delete iis configuration in your csproj file

[![enter image description here](https://i.stack.imgur.com/cHwXb.png)](https://i.stack.imgur.com/cHwXb.png)

yours could be different but should be similar to following

```
 <ProjectExtensions>
    <VisualStudio>
      <FlavorProperties GUID="{349c5851-65df-11da-9384-00065b846f21}">
        <WebProjectProperties>
          <UseIIS>True</UseIIS>
          <AutoAssignPort>True</AutoAssignPort>
          <DevelopmentServerPort>32049</DevelopmentServerPort>
          <DevelopmentServerVPath>/</DevelopmentServerVPath>
          <IISUrl>http://localhost:32049</IISUrl>
          <NTLMAuthentication>False</NTLMAuthentication>
          <UseCustomServer>False</UseCustomServer>
          <CustomServerUrl>
          </CustomServerUrl>
          <SaveServerSettingsInUserFile>False</SaveServerSettingsInUserFile>
        </WebProjectProperties>
      </FlavorProperties>
    </VisualStudio>
  </ProjectExtensions>

```