Dawn of the Dead was Romero's zombie film, as you know, which, in Italy, was called Zombie instead of Dawn of the Dead.
One year later, Lucio Fulci set out to make a zombie film of his own. He so respected Romero's 'Dawn' that he decided to create a kind of unofficial sequel, hence Zombi 2.
After that, a Zombie 3, 4, and 5 were made, all pretty lousy low-budget zombie flicks that were unrelated. Basically, if you were an Italian filmmaker and didn't know what to call your zombie movie, you'd simply tack it on to the legacy.
So if you're asking if Zombie 3, 4, or 5 run under different titles in the USA, they don't.
__________________
|