If you’re writing a workflow and are using the CreateTask or CreateTaskWithContentType activities you may come across the following error:
System.InvalidOperationException: Correlation value on declaration “Name of your token” is already initialized
When adding a token to the create task activity you will more than likely have set the OwnerActivityName property of CorrelationToken to the workflow itself.
The create task activity (and subsequent OnTaskCreated, OnTaskChanged and CompleteTask activities) should be contained within a Sequence activity (or a child type) and it is this that should be used for the OwnerActivityName property.
Ensure that all task activities contained in your sequence block use the same correlation token definition.