Doesn't matter. For a given speaking length (and pitch), the determinants of inharmonicity are the core wire diameter and the overall diameter of the wrapped portion
That being said, generally double wraps occur because the core wire is thinner and there's a maximum differential that can exist between the core wire diameter and the outer wrap diameter before you start having trouble with the wrap remaining tight to the core. Don't recall what that ratio is off the top of my head. The point being that a double wrap with a thinner core wire will have lower inharmonicity than the same outer diameter with a thicker core wire as you would see with a single wrap.