When the Nintex Workflow is started: Manually, on item creation, on item modification?
is the previous Workflow Completed or Terminated before the new one begins?
Yes it is updating the item. But the problem is in between email notification action is there. Hence it sending multiple notification to user for the same item.
I suggest to add Log actions before and after the Action that sends the mail with the name of the recipient.
Are you sure it is for the same item?
Is it always the same mail content?