I have tried toggling this previously, although it seems to no avail. It's possible that it's another hardware issue with the keyboard (this is the keyboard that short circuits after several minutes of hard use). Hopefully after exchanging it, this problem will be corrected.The touchpad is the same on both keyboard.
And I have 100% success rate. All I can think is that you don't type teh 2 fingers at the same time. You can check the option "Enhance Mouse pointer precision" which will help you with the multi-touch gestures and tracking of the cursor.
You can find it under the Mouse panel from the old Control Panel, then go under the Pointer Options tab.