Q: I have a MB Pro that is running Lion; I also have two external DVI monitors and a DVI splitter in hopes that I could run the two monitors with my MB Pro.   This actually works fine, but I am unable to "extend" the desktop.  Any insights?

You cannot have a extended desktop using a splitter.  All that does is mirror the pair attached to the splitter.

You can do this however using a Matrox DualHead2Go.

Other solution would be to attach one monitor to your video out as you do the splitter and attach the other via USB (assuming the adapter supports the monitor's resolution).

Newer Technology USB to DVI / HDMI / VGA HD Video Display Adapter

Hi there!

I have an early 2013 MBP with 15" Retina display. I am trying to use a dual screen as well with two 22" monitors. If I were to use the USB method, would that still require one monitor to be connected through a Mini Displayport / Thunderbolt port converted to DVI - Plus using one USB port for the second monitor? Or does that link you've provided do it all-in-one through the USB port?