[Game Play] New Black Cleaver Giving More Move Speed than Intended

I was playing Zed today and was really excited to try the new Black Cleaver on him. After completing Black cleaver from Phage I noticed that hitting multiple enemies with one of his abilities generated far more move speed than I expected from the items description. With no other items except for Black Cleaver and base boots, throwing an W, E, Q combo into a minion wave shot me to 427 move speed from 370. Hitting a single minion with one ability gave me the correct 20 additional move speed. It seems ad casters (and other champs too) are benefiting from from multiple bonuses. Can anyone else confirm? Rage passive listed below.

"Rage - Dealing physical damage grants 20 movement speed for 2 seconds. Killing any unit or receiving an assist on a champion that has any amount of Black Cleaver armor shred grants 60 movement speed for 2 seconds instead."