According to HKFA, they are the same person

Yin Chai (2) / (??) http://hkmdb.com/db/people/view.mhtml?i ... ay_set=eng

Yin Chai (3) / (?? (2)) http://hkmdb.com/db/people/view.mhtml?i ... ay_set=eng

can anyone confirm and update?

I dunno, Yin Chai ('Little Yin') also has musician credits in HKFA. I suspect it's just a common nickname, alias, pseudonym as in Andy Lau Tak-Wah being referred to as Wah Jai ?? or Tony Leung Chiu Wei as Wai Jai ??. Or Kenny Bee being called Ah B (remember the decorator in Koma?).
http://hkmdb.com/phpBB3/viewtopic.php?f ... nny#p72860