When I set up my wiki site (http://owfs.sf.net/wiki) I looked through the configuration file.
There is a section of meta tags for authors, copyright, licence. It is pre-filled out with the phpwiki name, team, and license. This information appears in the HTML source for every page generated.
It seems to me that the program source code should have the phpwiki name and copyright, but the wiki content (html pages generated) should be the site's perogative.
What is the appropriate practice?
This is just the default, which most people neglect to change. COPYRIGHTPAGE_TITLE, COPYRIGHTPAGE_URL, AUTHORPAGE_TITLE, and AUTHORPAGE_URL may all be set in the config.ini, and these apply to the page content.
The copyright notice for the wiki code itself shows up at the head of each file in the distribution.