Cause

For one or more targets at the first and/or second pin function connection, either created in the Plug Navigator or in the schematic, there are at least two form positions with the same name.

Solution

Double-click the pin in the Plug Navigator or in the schematic, and select the Connections tab in the Properties <...> dialog. Change the names of the form positions (that currently have the same name) for the targets at the first and/or second pin function connection.

Refresh the connections and then start a new check run.