Supposedly Harun had two sons called Shabbar & Shabbir.
So Shiis call al-Hassan and al-Hussein Shabbar & Shabbir (Hebrew names) which, apparently, when translated to Arabic mean al-Hassan and al-Hussein.
This is because the Prophet (saw) said to 'Ali that (You are to me as Harun was to Musa), so they take this literally and try to derive all sorts of meanings from it.
I still don't know what Zaynab is in Hebrew though...
Also, 'Ali had about 10x more children than Harun, I'm quite sure. So, it is all just very messed up.