Hi Unreal.
Downloaded yesterday the 4.7 preview 6, and there is a problem with the oculus. When you enter in stereo mode on , in all cases (inside preview vr in the editor, or launching a game and do a stereo on command, or building a standalone), it will work only one lense.
The oculus works well in 4.6.1 and worked well in the previus version of the preview version of the Engine.
Works well with all the other applictians outside Unreal.
This is what looks like
Another clue that I can give is that when I start the game in Extended Mode I have this warning/error before the game start.
I have only one graphic card , GeForce GTX 780 Ti , and the Oculus is plugged in the only slot for the HDMI of the card , then I have two monitors plugged with the DVI connector.