What you put into the template structure are merged together. The "old" HEAD elements that you put into the page structure are not merged together...
You can always see if and which HEAD elements have been inherited from the template on a page or article.
Code elements are the exception that proves the rule, because they function the same as in previous versions of SiteVision. The element is inherited from the page structure and not from templates. You can use code elements to add tracking code to your website for example.
You can edit additional HEAD elements created prior to upgrading to Site Vision 4.1 in classic editing mode. For these additional elements, inheritance remains unchanged even after the upgrade.
From SiteVision version 4.1, you need permission to "Manage functions for developers" in order to create and edit assets.