Matt Cutts replies with specifics on duplicate content

Now, think about it like a search engine who has come across the following situation:
– Two pages appear to have roughly the same content
– Page B has a subset of page A’s content
– Page A was published before page B
– Both pages use images from page A’s domain.
When it comes time to rank the two pages, which one do you put first? If you are a user, which page would you like to see at the top of your search results? How would you feel if you were site A?

The entire thread (link goes to Matt’s comments):
How Does Google Look at Duplicate Content?