I have an issue with some of our press releases ranking above the product page or for targeted page for a certain keyword because of the inbound links and such a press release can gather. There can be some risk of dup content, depending on how the PR is written in comparison to the pages it relates to. However, I have found dup to be less of a problem and keyword cannibalization to be a bigger one.
I have to go back in and update anchor text, links, etc. in the press releases to push some of the "juice" through to the product page we want to rank for those terms - definitely messy to undo and work with.
And I've never gotten really accurate data from ComScore, etc. so there's only so much you can uncover, eh?