Generator for Node.Key

is there a Factory for the values of Node.Key?
We decided to use GUIDs as the Node.Key, but when we do copy/paste the diagram is trying to manipulate the inserted key to ensure the clarity. But this results in Keys like:
bde691d6-721c-4084-8392-53ff837b32f2 2
bde691d6-721c-4084-8392-53ff837b32f2 3
bde691d6-721c-4084-8392-53ff837b32f2 4

If there was a Factory or a Generator-Callback we could simply return a new Guid and all is nice and clear.

Override the MakeNodeKeyUnique method, such as GoXam for WPF v3, to set the node data key the way that you want.