I've been fascinated by the discussions of the forthcoming Stones MONO box sets and it prompted me to get out a couple of my original LONDON pressings. When I did I discovered an oddity about the cover graphics of two different copies of the same album. The labels are the same maroon unboxed LONDON, "made in the USA," and the stamped matrix numbers are the same on both LPs. The covers are subtly different however. I researched all over this forum and the net and, while I can find plenty of info on label variations, I could find nothing about the covers.
First up - one version shows the LONDON logo in the upper right in reverse, i.e. white letters on a dark background, with the serial number nearby. The other shows the LONDON in positive, i.e. dark letters on a white background. The serial number and "MONO" are at the bottom.