Actually it is a big deal, entire blocks of flats have been banned because of one fraudulent clicker, Google is very protective of it's advertisers and will check through everything from your adress and telephone number to registered bank accounts with them to make sure fraudulent clicks are kept to a minimum Adsense do say why you were banned, in this case im pretty certain it was fraudulent clicks at least on the first occasion then re-opening with a banned account.
You should try to contact with adsense team to know what is the reason. And also stop making more accounts.