Reordering a page (via Space Tools -> Reorder Pages) that has Task List macros that include dates causes duplicate tasks to appear under "My Tasks" view
Workarounds can be found in this KB article
- Create a new page in a space that already has some pages in it.
- Add a task list macro, mention your own user account, add a date to the task (with '//').
- Go to My Tasks, notice the newly-added task is only shown once.
- Go into Space Tools > Re-order Pages, move the page with the task macro on it to above or below where it is now.
- Go back to My Tasks, and the task on that page is now shown twice.
The task will be duplicated each time the page is moved.