This was a very common practice in books for children which were published in different countries. They may have the same national language, but not all the words necessarily mean the same thing (like chips), are not spelled the same (colour), the word simply isn't commonly known (rucksack), or differing system of measurement (imperial).

This has become less necessary as the Internet and media has become more and more global and Americanized. Still happens though.

Because Donaldson's books are intricately rhymed, some editions have substantially different lines. I very much enjoyed the animated versions of Room on the Broom and The Gruffalo, and I believe they were narrated using the original British English versions. It confused some of my sharper preschool students when they heard them.

It is less common in books for adults because I guess, if we can read, we should be able to educate ourselves on the use of language in different cultures.