Not sure where that info originated from, I'm guessing it's talking about the Li Cheng versions?
The Li Cheng version of Diamond is technically 'longer' since it fixes the bug preventing you from finishing the first level, which was present in the English version and inherited from Super Mario Special 3 (where that level wasn't the first, but less of a problem in any case since you can select all levels from the start).
I don't know if there was an 'official' Chinese release of Diamond fixing the bug though, or if Li Cheng's was the only fixed one. And I have no clue about a Chinese release of Jade at all.