Single-Link refers to the type of DVI singnal - basically the bandwith / resolution it will go up to:
http://en.wikipedia.org/wiki/Digital_Visual_Interface

- Connect one at a time to the relevant output from the graphics card
- open the matrox GMX Control Panel
- select the resolutions you want to use (refer to the matrox instructions)
- reboot as necessary

do again for 2nd TH2G
(probably re-boot again)

-set the resolution in display preferences for the output 1 first

- then connect the 2nd TH2G and set the resolution in display preferences for that

hopefully it will work as required.

It is worth running remote desktop just incase you cant see the desktop at any point - then you can access it from another mac

S