Does Google Panda penalty apply to on site or off site content?

So many people say that Panda applies to content spread around the web. For instance, if you publish the same article on 100 websites, only one of those sites will be considered the author and rank for the content. However, could Panda more relevantly apply to duplicate content found on the same site? Such as if you have 100 pages all with similar content, but targeting slightly different keywords? In that situation, maybe only one of those pages would rank well while the others would not? Or, the entire site could be penalized. Tell me what you think of this idea.