I'm thinking about purchasing a turkey script that automatically grabs files from another site. My question is, will google drop the pages they've already listed?
First make sure its legal, if not you will have a bunch more issues. If your asking if google will not index the content if its already on another site the answer is no. It will still index it but it won't hold as much weight as the original, so it may not appear 2nd or not at all in particular searches.
No I was saying there are pages of original content that google has listed, will google drop these listings if they discover duplicate content on my site?
They may or may not. I strongly recommend to avoid copying the content previously index. If you have no other option at least you can rewrite it. NOT RECOMMENDED
I like how you said "turkey" script. I'd stay away from any turkey script myself if I were you, haha. I'd also stay away from anything that is a duplicate. If you can't help but to use duplicate content, see if you are capable of adding your own intro to the content, ie. a intro paragraph of your own unique content. That will help if you want to get indexed. Othewise it's better to create your own unique content even if it's harder to do.
duplicate content always has problems with search engines. So i'd suggest avoid it as much as possible.
Why would you do so? Just ensure always that your page content will be sensible enough to your visitors.