Connecting a second monitor

[jd]

Dear All,
I am running FC12 with all the current updates (to the minute).

I connected an external LCD monitor to my laptop's vga port.

I clicked System -> Administration -> Display

I do not see anywhere how I can configure an external monitor
connected to the same graphics card (i.e. NOT dual head),
but with different resolution settings.
Interestingly, the second monitor is automatically
treated as a span of the built-in laptop monitor, 
which is not what I want.

How can I set it up as a duplicate display monitor.
Win XP seems to let me use it as a dup display, and
with different resolution. I would appreciate any help
that would let me use it as a dup rather than a span
of the main monitor.

Best regards,

JD