When using OpenPlant modeler with a project connected to PlantSight, you cannot perform a "Save as" or "Copy and rename". This is because when you do “Save As” or “Copy” on A.DGN to lets say B.DGN, the GUID of the model is not changed. Plantsight has the GUID of the file written in its iModel, along with the file name. When you try to connect the Copied file it tries to match the file name with Original name and doesn’t find it so it creates the read-only connection to PlantSight. The request would be to have the "Save as" or "Copy and rename" create a new GUID during the process.