I would not know. I thought the Past Masters (for that is their real name) are packaged in a tiny 'LP' cardboard sleeve with the obligatory OBI. I never saw any advantage in these imitation LP sleeves anyway. But you could mail Amazon about it?
Well, given that they have no bonus tracks, I'm guessing that they are the versions that have been
mastered flat as alluded to by Bicyclerider:
A dub of the master tape was made with no noise reduction and no EQ, and sent to Japan and used as is to make the CD's - these CD's are basically like listening to the master tapes, as assembled by Brian and Chuck.
I guess its pleasing to see that these things are available. I am something of a completest, but I don't know that I can justify buying them all for a third time (I already have the 1990 and 2001 2fers). But the 'bass heavy and consequently a little "dark" sounding' aspect does kind of appeal...