Ironically you get so much more if you are NOT a HK resident. I applied in HK in 2017 before I got my HK visa with a passport that had about 3 years left (US) and got 10 year multiple entry. Previously I had only gotten 1 year (when I had a HK visa).
Such bizarre rules!
A business colleague in the US (never had a China visa in the past) also got a 10 year visa (applied from US) so that must be the deal with the US.
This has nothing to do with being a HK resident or not. The US and China made a reciprocal agreement in late 2014 that they would automatically issue 10 year tourist visas to each other. You probably just got the 1y visa before that and the 10y visa after that.