I think the best explanation is what was described in that quote I took from the Editdroid Special Features thread:
From what I remember, the "The Ultimate Supplemental Collection" by RowMan was designed to look like the Editdroid releases. This was in the days before we knew of the existance of the Editdroid Four Disc Special Features Set.
So Rowman originally created his set to be 'unofficial' bonus discs to the Editdroid OT movie DVDs. However, at that time, no one knew the Editdroid team had also produced their own 'official Editdroid' Special Features Set.
Both sets are worth having as they feature different content, although both share the 'Making of' docs taken from different sources. And you're in luck as the four 'official' Editdroid Special Features discs are currently being posted to alt.binaries.starwars.
Hope that helps.