When adding a comment, the timestamp is different from the time of the client.
In the document view and on the properties tab of the content/item the timestamp (server time) is different from the timestamp in the history (client time).
For example: It is confusing for the users when an content/item is created on Oct 25, 2017 9:55:40 AM (client time) and the comment is created 2 hours earlier on Oct 25, 2017 7:56:52 AM because the displayed timestamp is server time. Therefore the question "how can a comment be created before the related content/item?" appears often.
It should be possible to choose which time (server or client) should be displayed for the comment.