Steps to reproduce:

open two magnolia instance with different users logged (superuser, eric):

1) as superuser open sporstation page

2) as eric open the same page (superuser gets notification about this)

3) as superuser open "edit page properties" dialog, update "navigation title" field and save changes

4) eric gets "pending changes" notification eight times in a row

Basic observation: This is a bit bypassed in M5 by auto-closing notification after delay. If user does nothing, all notification are closed automaticaly. Bug can be seen if one tries to close notification before self-closing. Behaviour is a bit different in M6 as notifications disappear sequentially one after another always with new closing delay (so delay is way to long in described case).