The American version of this set featured 10 sticker/card combo cards, which required peeling off the sticker to reveal a completely different image on the underlying card. The card backs featured captions describing both images.

For the Canadian edition the stickers (1-10) and cards (11-20) were issued separately for a total set size of 20. And I suspect they only did this because they had to make the card backs bilingual and thus couldn't fit the English and French versions of both captions on the same card.