The fake chesnut vendors or not
Brandy Yuen Jan Yeung ... Fake chestnut vendor
and
Yuen Shun-Yi ... Fake chestnut vendor

I'm very very sure!

You are right.
The fake chesnut vendors are not the two Yuens. One is unknown to me and the other one is in many movies like "The Delinquent" but I don't know his name.

It was me who added the two Yuens to the cast list, but for other roles in the movie (brief extra appearences). Another editor added later the wrong role names. Changed the role names to "extra".