Originally Posted by AaronP
For the most part, you can think of RandR 1.2 as being equivalent to TwinView..
The operative phrase is "For the most part." There are things that XRandR 1.2 can do that TwinView can not. For example, it is possible to use a dual monitor XRandR 1.2 machine for color critical work because it supports separate video card gamma tables for each connected monitor and TwinView does not.