Very nice. This combo works because he was frozen and got hit by the uppercut at the exact same time, I'm guessing instead of counting it as 1 hit, it counted it as zero hits because the clone wouldn't be a hit, and in all other double hit scenarios, it counts as one hit, ie: Jade Return Boomerang + any hit. It's not like the scream which has some broken built in properties. Never suspected this however but it makes sense.
I think you could max this combo out to HPHPHP, JK, JK, HK at the end which would add about 12% to the combo for damage sake.