Duplicate resource error

When I try to add a resource to my project's .res file, I get a "Duplicate Resource" error when linking. The resource I have added is a unique resource. How can I successfully add the resource to my project?

The projects resource file is generated by the IDE wizard, and is not intended to be modified. To add additional resources to your project, create a separate resource file with a unique name that does not conflict with either the project or any of  the unit names. Then to add the resource file to Delphi, simply add the following line to any unit file in the project:

{$R MyRes.Res}

(where MyRes.Res is the name of the resource file).

To add the resource to Borland's C++ Builder, add the resource

from the project manager.