Getting the job done in as easy and simple a manner as possible.
That’s the annoying message I got after activating the workflow feature and then trying to edit the workflow in SharePoint Designer.
The exact steps were as follows:
SharePoint 2010 FetchlegalWorkflowActions SOAP exception: System.ArgumentException: An item with the same key has already been added.
To resolve this just undeploy and remove the Farm solution! See this post for someone else who discovered this: