yours doesnt check ident or nick though only hostname.. or am i missing something
It doesn't need to. It's banning any nick having your same host mask - that isn't you. The "!" prefix prevents it from matching your own join, though since you join without OP you couldn't ban yourself. The @ prefix would probably be better since you could only be OP if the join weren't yourself.
This code would also ban a 2nd nick joining from your own PC.