When Amos put together the first set of Mudcat CDs (the Blueplate Specials), I bought one complete set and or or 5 more of the one I had a song on. IIRC, Dick let me purchase all 9 or 10 of them for $12 apiece.
That makes sense to me, since it does encourage buying in bulk, or "multiple copies," no matter which assemblage of CDs you select.