title_body: Is there any ereader that can split the document in to 2 I am looking for an ereader that allow me to split the screen in to 2, so that I can read different pages of a file at the same time, or I even can open 2 files together?
  
  I have searched a lot but have found nothing about this.
upvoted_answer: You didn't mention what platform you wanted (iOS, Android, Fire, etc) so I'll just answer this the best I can for Android.
  
  Android OS has a feature where you can run 2 apps at the same time - so you could run any e-reader app on both sides, and open different documents.  If the e-reader app itself didn't like running twice, I'm sure you could just use 2 different e-reader apps of your liking.
  
  If your Android device does not already have MultiWindow capability, then you can install a package like XPosed (you can find instructions here) that will (in some cases) give you that capability.
  
  Note that on the Samsung devices where multiscreen is built in, not all apps are supported.  In order to get around this limitation, you can install an app like MultiWindow Apps Manager that allows you to specify which apps should be listed.
  
  Hope that helps!