Using Public Domain Texts on Our Website: Do We Have A Duplicate Content Problem?

We are creating a site that will hold quite a few public domain texts (historical writings, literature, speeches etc.). Those texts can be found anywhere else on the internet, in the exact same format. Our texts are slightly annotated and have a some color and borders around them, to highlight a few things.

Is this a duplicate content issue? What would you advise us to do to make sure we are getting indexed? I do think that we are adding value here, with these texts, but I am not sure if Google would understand that, since, on the face of it, the displayed texts are identical to other texts on the web.