Both have been circulated, the pink one I tired wiping it off but was still in tact, the other one has the same yellow tint on the back,
I'll get a picture
From my observations variations in tint happen because of the varying intensity of the colour on solids and more frequently due to a bit of "smudging" of microprinting. The "smudging" results in microprint that is thicker than normal changing the appearance of the colour/tint.
The strange thing about the tint and intensity in the images that were shown is that the manifestation happens in the middle of the intaglio printed elements. From my knowledge the central portion of the portrait has no microprinting (i.e. no elements printed with offset lithography) so it is just not possible to have a change in tint due to the two reasons mentioned above.
Could it be that there was some colour spread from the intaglio printing? Possibility but that would not explain the note with the pink tint which has a very definite shape. It would also not explain the spread of colour to non intaglio printed area except if it was due to the plate roller not cleaned properly.
If you are interested in further investigation of these notes PM me and I can give you some suggestions.
If you find more information on these conditions please do share it.
