MSB4011
This diagnostic code is emitted when you import the same project more than once in the same project file.
The full message resembles the following text:
'project' cannot be imported again. It was already imported at ''. This is most likely a build authoring error. This subsequent import will be ignored.
The same project appeared in more than one import element. While this is not a blocking error, removing the duplicate import element eliminates this warning.
Be aware that if an imported file uses properties and items defined in your project file, the placement of an import element might affect the behavior of the build. Therefore, it's important to understand any differences in property values or items that are used in the imported project when choosing which duplicate to remove.