I remember seeing it onsale at record fairs. cant find it on discogs but here's the last.fm pages:
http://www.last.fm/music/Underworld/...6+%28disc+1%29
http://www.last.fm/music/Underworld/...6+%28disc+2%29
They stuck some other tracks on the end of disc 2.. i think Jamscraper may have been one. Even as a bootleg i'd say its quite rare. But it was recorded 3% too fast and there are pops and clicks and sometimes channel dropouts. The version on RTSR is cleaned up and speed corrected.
Its never sounded so good.