I have a related issue. My daughter has managed to drag her top panel to the left hand side and I'm having no luck in moving it back. Right clicking and going to properties informs me that the orentation property is locked down.
I've tried using gconf-editor (apps" > "panel" > "global", and unchecking the key called "locked_down"), tried
gconftool -t bool -s /apps/panel/global/locked_down false
and the bugger just refuses to let me return it to the top. Is there anything I can do that doesn't involve reinstallation ?
EDIT: I opted to delete the panel and start from scratch. FWIW if you run any of the standard methods of returning to the default panels you get a single, unipurpose top panel.