The Own classification consists of a maximum of 4 layers. If the same ID appears on one layer with different descriptions, you will receive this error message. It is best to leave the IDs unchanged. If a new item is to be added to the same layer, the ID should be left blank. Leave the ID unchanged to prevent error messages.
Solution:
Find the IDs that occur more than once with different descriptions and either align the descriptions or remove the IDs from the new items to be added.
