Nope. That is just the way it has been when I got myself banned.
Banned users can register under different name and thus bypass the ban. Only the account gets banned here. There is always an IP ban option, giving that the spammer has a static IP address (which is highly unlikely), but Dani refuses to go that far, because of the possible collateral damage. Here in Croatia, one has to actually pay extra for static IP address. All I need to do to change my IP address is to reconnect to ISP.
But, if the spammer is using my ISP, it is possible, by banning his IP address (in reality, ISP server's IP address), to ban me as well.