This is actually what I meant by "merged together". They are two separate displays controlled by separate computers, with separate power supplies etc. During normal mode operation they're synchronized somehow and can draw a large image over the entire display area, but in emergency mode you can display crucial flight data on only one of them if the other stop working.

I have never really thought much about it, but I guess the actual LCD thingie is manufactured in one piece and the control signals just being split between different computers somehow, but I don't know anything about how these things are made! :)