Scenario from my work, why this is needed:
I create a Use Case diagram as a system overview (or definition of system and system context).
Next step is I create a refined Use Case diagram that will contain many of the use cases of the overview diagram and adds new one, however sometimes the names might be slightly different. In the refined Use Case diagram, I would also use include and extend relationships between use cases.
Currently, I cannot just copy and paste the original Use Case diagram into a new model and start changing things, since all elements are just views and would result in changes of the original. I have to manually create everything again! Waste of time!
All would be easier if I could just copy the original and PASTE CLONE and then start changing things.
Yes, I would also encourage that feature, which is available in all other UML tools that I have reviewed so far.
You could have two Paste options:
Paste View (view of a model entity that still refers to it and changes when original changes)
Paste Clone (creates a new model entity, exactly like the source but without any reference to the original)
In addition, in the model explorer, there should be a color coding of Model element names so specify if it is the original or a view.
DRAKON diagram does not seem to be UML?