The solution is to add a child-pane and not a multi-value.
Add this node to the root.plist file:
Type PSChildPaneSpecifier Key About Title About File About
And then create an About.plist file (add it to the settings.bundle from the Finder: view package content and then add the file manually.
The file should look like this:
Strings Filename About PreferenceSpecifiers Title Type PSGroupSpecifier FooterText Bla Bla Bla