Duplicate content is a case of percentages – if all of your content is exactly the same as found elsewhere (e.g. Affiliate feed) then that can be considered duplicate content and cause your web page (or website) not to rank.

However, if your content contains only a small amount of content from elsewhere and you have added value to the original source (e.g. Recipe list in an article or content creation) then it may not be considered duplicate.

Matt Cutts explains the difference in the video below.