Two pages at a time can be displayed in LIVE, either vertically (side by side) or horizontally (one on top of the other). Each page shares equal space on the screen but can be scrolled or annotated independently by clicking the area of the screen you wish to be active.
Hotkeys to display multiple pages are "/" to display vertically and "\" to display horizontally. Once multi-page display is engaged, to display media in the second area, you will need to make the second area active by clicking on the space or using Tab to move to the other side, then either manually enter the Media ID (X+ID), or selecting a media in Production and sending to LIVE. Pressing the multipage hotkey again will go back to single-page display of whichever page is active.
CTRL+/ will instantly display the current page and display the next page of the document to its side. CTRL+\ will do the same, but put the next page on the bottom half of the screen.