|There can be only one|
Deleting history is not the solution. You can use File>Optimize scene to delete those nodes, but I wanted to know the truth about this extra nodes.
After examining for a while those nodes I found the obvious solution: if you have (for example) 2 shapeOrig on a mesh object, only one is the correct node, other one is simply rubbish. How to detect which one to delete? Simply as hell, the good one has an output connection, the other is simply watching time passing by with no connection.
|Output connections, that's the real shapeOrig that is being used by deformers|
|No connections, safe to delete.|
That's it. Hope it helps.