The number of Notifications in the counter and the ones listed don't match in Subwikis

Preconditions: A subwiki must be created with both global and local users or just global. A global user or local user must be created and part of that subwiki.

Steps to reproduce:

1. Login as a user that is part of that subwiki (e.g. globaluser01 or localuser01) and set Pages notifications to ON - in the Notification Menu column 
2. Login as Admin on the subwiki and create 5 pages
3. Update each page by adding any text
4. Add a comment in each page (at this point there are 15 notifications)
5. Update 3 of the pages again by adding text
6. Login as localuser01 or globaluser01 in that subwikis and observe the number shown in the counter then load all notifications from the list

Expected results: The number of notifications shown in the counter are the same as the number from the notification list.

Actual tesults: The number in the counter remains as 15 but in the Notifications list there are 18 entries. The same issue reproduces with local and global user.

NOTE: I think it's an issue maybe related to https://jira.xwiki.org/browse/XWIKI-14719.

The Edit event appears 2 times separetly ex. "Page 1
edited by Administrator 9 minutes ago" and "Page 1 edited by Administrator 11 minutes ago". The Edit page should appears just 1 time and when clicking on "..." the user should see information about 2 events taken place at diffrent times.