If there are multiple changes made on same day, currently only the most recent change on a single day has a date displayed and rest of the changes that day display only the change time. It was felt that only showing each date once would simplify the display, however, since the entities are not grouped together this display can be a bit confusing for the user.
MDL-30279 will change the display so all change dates will be displayed. However it was felt that if the items were grouped properly the original intention of showing a single date per day would be better.
This issue has been created to improve this display in future, so that we are not showing duplicate dates on the history tab. Ideas for how the wiki changes could be grouped together in an obvious way are welcome.