That’s right. The example I posted (No 2nd screen w/nVidia v260.1.19.36 and 11.3) doesn’t use Xinerama.
# **********************************************************************
# Server flags section.
# **********************************************************************
Section "ServerFlags"
Option "AIGLX" "on"
Option "Xinerama" "0"
EndSection
...
...
# **********************************************************************
# ServerLayout sections.
# **********************************************************************
Section "ServerLayout"
Identifier "Dual"
Screen 0 "Screen2" 0 0
Option "Clone" "off"
Option "Xinerama" "off"
EndSection