I suspect the already artificially? toned coin may have been submitted for grading and slabbed for preservation.
As far as toning is concerned,
perhaps PCGS saw it as a borderline case of deciding between artificial and natural.
Others may have a different opinion.
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? How much does beautiful artificial toning detract from value?
Personally, such beautiful toning, be it artificial or natural, makes zero difference to me as far as value is concerned,
because such toning is unstable in the long term.