Flip Writer lets you type a message on the keyboard, and this message is displayed on two displays,
Source: As Scooped from: http://attraining.org/atdaily/2014/09/30/two-displays/
AT Daily reviews Flip Writer app. Free, with in-app purchase for word prediction, provides a flipped display for a communication partner. Wow, I remember when these types of devices were specialized and quite expensive . Flip Writer AAC is developed by the creators of Spell Better.
If you need a text based communication device, check this out.