This has been puzzling me for a long time: when it comes to workboards, there are 2 distinct URLs to the exact same Phabricator "page" e.g.:
Look exactly the same and show the exact same content.
I don't think this behavior exists anywhere else in Phabricator. I would qualify this as a bug as I would argue that each section / page of a product like Phabricator should have a unique URL. IMO the tag should simply redirect to the project one, which appear to be the root path for Projects anyway.