Radeon HD 3470 dual monitors on Squeeze

[Rob Owens <rowens@ptd.net>]

I've been trying to get dual monitors to work on my Squeeze system.
Originally I was using both the onboard video and an additional video
card.  Now I have two monitors hooked up to the same video card (thanks
to a cheap craigslist purchase).

When I begin booting, both monitors give me a display.  But when the
boot process gets to the point where text display changes (framebuffer
turning on?) one monitor goes blank and I cannot get it working again,
even when logged into a GUI.

Both monitors work properly with Knoppix 6.4.4.  I tried using the
Knoppix xorg.conf, but that did not work.  Here are some differences
between Squeeze and Knoppix:

				Squeeze		Knoppix
kernel:				2.6.32-5	2.6.37
xserver-xorg-video-radeon:	1:6.13.1-2	1:6.13.2-1
libdrm-radeon1:			2.4.23-0.0	2.4.23-1
radeontool:			none		1.6.1-1

I don't know if the above differences are important or not.  

Any ideas why one monitor always goes blank in Squeeze?

-Rob