Multiple <ext> files - only one is allowed
A request was made to save changes to a project, but more than one
file with the extension <ext> was added to the list of files in
the project. The current project template allows only one file
with the specified extension in the project.
This can happen, for example, if you add more than one module-
definition (.DEF) file to a project.
Delete the extra file from the list.
-♦-