Hmmm, so the documentation for [BadgeAssertion](https://github.com/mozilla/openbadges/wiki/Assertions#badgeassertion) objects say that `uid` is:

> Unique Identifier for the badge. This is expected to be **locally** unique on a per-origin basis, not globally unique.

And from [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Same_origin_policy_for_JavaScript):

> Two pages have the same origin if the protocol, port (if one is specified), and host are the same for both pages.

So two separate departments issuing badges from the same origin but different URLs would, to anything conforming to the 1.0 spec, be the same issuer... and therefore any badges they issue *must* have different GUIDs.  This may or may not be a good thing, but it's part of the 1.0 spec, and not something that this GUID-generating function can change, as far as I know.