Hello Yves,

You can configure the Matrox also as a dual head. Last time I had the same problem. If you configure the triple head2go as a dual head, then output 2 will be disabled.

On the website of Matrox you can download the program called "Matrox PowerDesk for Mac" in this program you can configure the Matrox Triple H2Go.

Hope this helps.

Kind Regards,

Erik-Jan Berendsen