seeing double when translating Vive HMD

When I move my head from side to side, or up and down, the edges of objects are shown doubled, as if there is a short trail or a delay as it catches up to itself. Also, if I close one eye, I can still see it. But if I rotate my head I don’t see this. Any idea what this is and how to solve it?
I’m using a Vive.

  1. What trouble shooting steps have you taken to narrow this down?
    -Have you tried a blank project?
    -Have you tried a different game?
    -Have you tried a different character / camera setup?
    -Have you tried a different HMD?

Yes, I have tried with a blank project, and the VR Template, and the VR Content Example. I don’t have a second Vive to test with.
I’ve seen it in some games too. I don’t know if all of them have this. I am not the only one experiencing this:

I have a gtx 1070 and an i7-6700k so I don’t think it is an underperformance. Someone there mentioned interlacing? Or reprojection?

This is clearly due to me adding a renderTargetMultiplier into the steamVR options. Removing it removed the doubling effect. Now if only i knew what this option really did …