Did you check the domains? The numbers alone might not seem spammy, but there are domains with high authority that have been causing Penguin problems. A lot of directory links, any domain with Article in the title, things of that sort. I would try using Majestic and SEMRush for a comparison.
Even with that information, I am not convinced that the duplicate content is enough. I would test it by adding 200-300 words of unique copy above the duplicate content on the pages to see if helps the rankings at all. That will be more cost effective than completely rewriting content first.
