I have just noticed that Google has started indexing .pdf pages on my site. Really I dont mind this as the .pdfs contain a lot of relative information that I hope will aid my ranking. However, the .pdf's contain information that is taken directly from the site. Will this have an adverse effect? Just worried about duplicate information being penalised by Google!
A lot of sites use pdf's for printable versions of pages and for a variety of reasons. This is good practice and helps the users of the site in many ways. I am sure google knows this and would not apply and duplicate content penalty. As I understand it the duplicate content penalty is intended to stop sites benefitting from having duplicate content - your pdfs will give you no benefit in terms of search engine rankings so the penalty would not need to be applied.
Yeah, most respectable websites (particularly universities) have a printable pdf version of the pages content. I'm sure Google has some sorty of exeption to account for this.