Hm, interesting. I’ve been trying it for another hour with the slightly advanced opponent ;), and can’t land a second hit. It’s always the same: I parry, during the “sword time” press attack, the hit lands and then I cannot do anything (controls basically do not react) for a pretty long time, it feels like a second or so, while the opponent is recovering. What is even worse, if I press attack again during this time when the controls do not react, Henry attacks right after the opponent has recovered, and this attack is 100% parried or dodged.
EDIT: I just watched the Alpha 0.4 live stream and Viktor attacks a few times after a successful parry, but always only lands one hit.
During training, I’ve unfortunately left the area and I’m not going to try it again 

Since the combat is so awesome and satisfying (especially long parry-counter-parry sequences are badass), the bugs become really noticeable.