Where does "Added By" value come from?
When you access Civi, you log into your CMS (Joomla in this case) with a CMS account. That CMS account "Joomla Administrator" will be linked to a Civi contact. My guess is that your "Joomla Administrator" account is linked to the "Test Gmail" Civi contact. You can check this by looking at "Test Gmail" summary page in Civi: "Contact ID / User ID" will show Civi's ID for the contact and Joomla's ID for any linked account. A Joomla ID will have a clickable link that will take you to the Joomla Account profile.