Visual InterDev
You are trying to add a built output file to a folder in your Web project and a built component with the same name from another project or the same project already exists in the folder. Built outputs come from other applications such as Microsoft® Visual J++™, and can be added to your Web project. This error occurs while you're adding built outputs; another output has the same name as one you're adding.
-or-
Remove the previous project output dependency.
For more information, see Building a Solution or Project.