Walking With a Ghost is a mostly live album (EP) by the White Stripes. The title song "Walking With a Ghost" is a nice cover of Tegan and Sara. The musical style is reminiscent of their album "Get Behind me Satan" which was released just previously. It's somewhere between "Blue Orchid" and "Icky Thump". Having not heard the original song I would have thought it was the natural evolution of their style and sound, but listen to Tegan and Sara's version.
And compare it to the White Strips
If you go listen to Icky Thump, it all very similar in style. I don't know Tegan and Sara too well, so I looked them up. You Tubing around finds a bunch of their songs and they've all gone different direction then Icky Thump. Which leads me to believe that Jack and Meg heard this lone song and liked it's style, so they covered it. (I'm not saying they don't like the others.) After all it does groove with their sound. It's nice to discover where some of their musical influences come from.