SC #907 Color Difference

Sorting thru a pile of stamps I came across several Sc 907's. Normally a rather mundane stamp. Scott says that they should be Rose Carmine, but I found a pair that are closer to Lake with no back ground color.

I though a color changeling, but both (Lake) stamps are too consistent.




Thoughts?

Opinion / Suggestion,
(Not a US specialist)
The Left hand stamps are the genuine original colour, sullied by time, storage and handling.
The Right hand stamps, damaged by soaking in hot water,
evidenced by the ink bleed outside the image borders ?

So, a quick experiment. 4 Scott 907's:
First - original as removed from the envelop
Second - soaked for 10 minutes in a 3% solution of H2O2
Third - soaked in very hot water for 10 minutes, ink bleed is apparent
Forth - stamp with color in question



It doesn't appear that soaking the stamp caused the color to change or at least not dramatically. I'm of the opinion that the stamp was printed in a Lake color.

Two observations/questions.

1. ink bleed vs plate wiping: poor plate wiping would also create a slight pink tinge to the surface of the front of the stamp - printed during war-time conditions. It would be interesting to see the reverse sides for evidence of ink bleed. Poor plate wiping will show on the surface of the stamp, ink bleed will be into paper of the stamp.

2. the dingy pair has a parcel post roller cancel and toning. This cancel and toning combination would be consistent with being on a corrugated box for many years before soaking. What does the back side look like?

Back of the dingy pair. The back appears pinkish in the scan, but in day light it is the same dingy white as the front.

I just looked at my examples of the 2c
Mint and otherwise.
I would (for mine) go with John's suggestion of "poor plate wiping"
not ink bleed.
I have the 2 examples similar to Moyocks.
I sit with Rose Carmine.

Just a simple question. The Scott 907 was a rotary press stamp. Did they wipe rotary press plates? I plead ignorance!