>Edit: They did change the image. In the last image, they showed a metal surface which wrapped two times and had not the properties of a mobius strip.

This is still a single-sided surface though (with the 2 twists).

Wikipedia: "the Möbius strip can also be formed by twisting the strip an odd number of times greater than one"

Not sure about needing to be "odd", I think 2 qualifies as well, so perhaps odd or even AND prime does it...