Yes, but some times one string from whole html can not be unique, does it mean that whole document is not unique ? if Not, How you can find out that ?
You look at both documents and determine yourself the level of uniqueness. If the second only contains that one sentence and but several unique paragraphs, it would be about 95% or more unique wouldn't it? The more unique your content is from other content the better. However you can still rank with duplicate content, even #1 but it's alot easier with unique stuff.
sure I can do that, but I was looking for a tool that can say for sure is that unique content or its not