For some time now I have been having duplicate tasks show up on my iPhone 4S and 4th generation iPad. This happens as soon as the task is created. When I "complete" one of the duplicate tasks in order to get rid of it, the other also disappears, and so I have to recreate the task again (with no guarantee that the duplication won't appear again). If I add a note after creating the task, the note only appears in one, not both, tasks, but regardless of which task I delete (i.e. check off as "complete" in order to remove the redundant task), both versions of the task disappear.