Unfortunately there is no easy way to know.  The license certainly goes beyond saying that in that it just doesn't merely refer to source, it refers to source and documents.  I agree it's quite reasonable to assume the builders have licensed their work to the Diku team and have authorized the distribution as a collective work.  

Still this issue was one that was beat around usenet for quite awhile.  We agree that these assumptions are reasonable.  We may not agree with how you get there, technically.  I think we both agree there's no fraud on the part Diku, Merc and Rom groups.

What I'm not getting is why you brought it up?   It doesn't seem to have a bearing on the issue of taking works and appropriating them into muds.  Especially when there isn't any assumptions to make about the Tolkein works.  The only assumption one can reasonably make in regard to current law is, "No I can't do it".

Now should for some reason say if someone named Redferne comes out and says, Hey I never wanted my area distributed with Diku, I think we're all obliged to delete the Diku distributions we carry on our sites (or removed the offending pieces) and remove the area from our muds.  *shiver*

Still I'm not sure where you were trying to lead me with this.  ;-)