Notifications shouldn't be duplicated in Notification Menu

Preconditions: A simple user (e.g. U1) must be created.

STEPS TO REPRODUCE

1. Login as a user (e.g. U1) and set all notifications to ON (Notification Menu + Email, choose Hourly)
2. Login as Admin and create a page, update it, add a comment and delete it
3. Trigger the e-mail sending from Job Scheduler (xwiki/bin/view/Scheduler/)
4. Login as a user (e.g. U1) and observe the Notification Menu and the e-mail received

EXPECTED RESULTS

On the user's Notification Menu and on the e-mail received, the events related to the page modifications made by Admin (create, update, comment and delete) are displayed one single time per event.

ACTUAL RESULTS

On the user's Notification Menu, the page create event is displayed twice (screenshot attached). However, on the e-mail received, the notifications are displayed correctly.