PDF reader with split screen for Linux

evince 2.30 can at least open two separare windows for the same PDF document. Open a PDF file, then choose File->Open a Copy. Now you have the same document in two windows.

This is a bit of a strange answer, but Konqueror (the default everything-browser for KDE) can do what you want. You see, Konqueror is not just a web browser or just a file browser -- it is a browser for any type of data that there exists a KPart for (where a KPart is some type of component that KDE can understand and embed places -- things like Konsoles, Kate windows, and -- of interest on this occasion -- KPDF viewers).

Thus, because Konqueror has a split view, you automatically get a split-viewable PDF reader for free. Just open up a Konqueror window, split its view, and open up the PDF in each pane. Each can scroll independently of each other, etc.

You'll have some of the basic PDF-browsing features but not some others -- KParts are not meant to be full applications. Thus, you won't (for example) be able to annotate the PDF in Konqueror as you would be able to in Okular, for instance. But as long as you just want basic viewing, this will be enough :)

KParts and all the modularity of the KDE framework allows for some pretty neat stuff, in my opinion.

Emacs 23 (and earlier versions with the separately obtained doc-view.el package) can seamlessly open and view PDF files. And using the usual split window support (C-x 2) you can display two different parts of the same document in the same window.

I doubt that this is going to be as easy to use as just opening a normal PDF twice, but it definitely does exactly what you ask for.