Soseiru
It just be a misshap that happened in the printed process. Those mistakes happen a lot. It's why when transfered from a manga Sailor Pluto's white and she's African American in the manga, but ever once and awhile the printers would render Takauchi's drawing wrong.
'Every once in a while,' not for every copy.
Is that always a mishap? I thought sometimes tone was missed off becausae the artist couldn't be bothered, like for small panels and things.