@spg, that odd toning looks more like chemical exposure to me. Some liquid may have splashed on this coin. Also, since best practice is to only post a single coin per thread, I'm going to try to split off your other coin into its own thread.
"If you climb a good tree, you get a push." -----Ghanaian proverb
"The danger we all now face is distinguishing between what is authentic and what is performed." -----King Adz
The staining you see is not an error--it's post-strike damage, likely caused by exposure to a chemically-active liquid. Not that uncommon. Given the photos posted, can't determine what might be going on with the designer's initials. Close-in, large and sharp pic needed.
The Incuse devices have a high percentage of Machine Doubling on these quarters. On survey I conducted, put it a 70% of these quarters were affected, from slight to heavy Machine Doubling. The DDR's on these quarters (Single Squeeze Dies) Affects the areas towards the center of the design, Never on this area. No DDR's have been on this area of the design.