You can copy a diagram element and paste it into the
same or another modeling diagram.
When you copy a diagram element, the corresponding
model element is not copied and does not appear in the Model Explorer view.
To copy connectors, you must copy both the connected diagram elements
and the connector.
To copy a diagram element:
Open a diagram that contains the diagram elements
that you want to copy.
In the diagram editor, right-click a diagram element;
then click Edit > Copy.
In the new location, right-click; then click Edit > Paste.