Originally the movie was called Halloween 7: Two Faces Of Evil. This first script was written by by Robert Zappia, before Jamie Lee Curtis pitched her idea to the studios.
When this happened, Dimension films contacted Kevin Williamson and asked him to rewrite it, but he declined. So they brought Zappia back to rewrite it.
The second script is Halloween H20: Twenty Years Later written by both Robert Zappia and Matthew Greenberg.
In early 1998, Jamie didn’t like the script, and asked Kevin Williamson if he could rewrite it. Since it was Jamie who asked him, he agreed. According to Kevin, they shut production down for a week while he did a full script rewrite. He kept certain concepts and characters, but performed a full rewrite on the story.
I found the first two scripts, but haven’t been able to find the one written by Kevin Williamson.