The books which I consider to be the Taiwanese editions are apparently unlicensed versions of their American counterparts. I have also heard rumors that these have been found in the Hong Kong street markets. Despite the fact that they are bootlegs, they are easily distinguishable from the true Grosset & Dunlap editions - mostly by the copyright page which has the Chinese paragraph displayed below. Also, they are just slightly over 1/2" thick and the corners are more square; because the spine is slimmer, the size of the text (title, author's name, logo, etc.) is smaller, and you practically need to borrow Nancy's magnifying glass to read it.
Jennifer White of the Series Books for Girls fame did a blog entry on this topic in 2011 where you can see the variety of these formats available on the "black market."
© 1998, 2016 Lea Shangraw Fox