A "Dual Page PDF" refers to a specific file structuring where two logical pages of the book are displayed simultaneously, simulating an open physical book (a "spread").
Common method:
This refers to a digital scan or typeset PDF of the Madani Mushaf (commonly printed by King Fahd Glorious Quran Printing Complex in Medina) where each page contains 13 lines of Arabic script, and the PDF is formatted to display two facing pages side-by-side (like an open physical book). 13 line quran dual page pdf