Those two stamps were issued in 1894 in the Netherlands. The 10-cent stamps depict Queen Wilhelmina as a young girl.
The mystery is that the U.S. Scott stamp catalogue does not list the colour pink(at right) for this issue. Rather, Scott lists bright-rose(at left) for this issue, and brick-red(43a). But the pink copy at right is not a bright-rose to my eyes, and certainly not brick-red.
I don't remember exactly where I got these two stamps; perhaps from one of the two dealers that were in business at the time in the city where I used to live, but are no longer there. This would've been in the 1990s.
Some time after acquiring the two, I did read online, many years ago, about the existence of a pink colour-variety for this issue, but it is exceedingly rare. There was no image provided with the article or comment at the time. The question is is this the said rarity after all, or was mine once bright-rose, but then had been exposed to sunlight for a long period of time and faded; laying on a window-sill, or on top of a desk or table?
Thank you for looking.