Answer
A duplicate workflow is usually created when Create is selected during publishing instead of Update.
To update an existing workflow, you must choose Update when publishing. Choosing Create makes a new workflow instead of updating the existing one.
Steps
Open the existing workflow and save it as a draft.
Make your changes.
Publish the draft.
When prompted, select Update (pencil icon)
Select the Group(s) and Publish.
Refresh the browser to ensure the latest version is available in Editor.
Use Update to replace the existing workflow for future use.
Use Create only when you intentionally want a new workflow.
If you publish an existing workflow to a new Workflow Category using Create, ANVL will always create a duplicate. If that happens, contact ANVL Support to have the duplicate removed.