Cause

A planning object occurs more than once in the project with the same designation.

Solution

1. Locate the planning object that occurs several times by using the functionalities Go to (graphic), Go to (2nd coordinate) or Synchronize selection, which the popup menu of the Message management dialog offers you.
2. Call up the Properties <...> dialog of the planning object and bring the <Planning object - displayed name> tab to the front.
3. In the Designation field, change the character string, so that a unique planning object is stored in the project.
4. Click [OK].
5. If required, start a new check run.