
http://hkmdb.com/db/movies/images.mhtml?id=5954&display_set=eng
This seems to be Alan Chan Gwok-Kuen

which would validate the "Chan Kuen alias" theory, except he's a very minor character - doesn't speak (or really do anything), so it seems strange that he would be in the credits when other actors with bigger roles are not. Maybe the DVD is cut, and his role was originally bigger?