background-repeat: repeat-x, repeat-y; Webkit does not drop this wrong declaration. One 'row' and one 'column' of the background-image are rendered.
See: http://www.w3.org/TR/2005/WD-css3-background-20050216/#layering This is CSS3 multiple backgrounds. The current wording of the draft has the # of layers set to: N = max(M, R, S, P) [shouldn't it be M instead?] At least with the current draft, this is not a bug. You have requested two layers, and the image is being rendered twice (once with repeat-x and once with repeat-y). There is a note that says "shouldn't it be M instead" in which case this would be a bug, but there are use cases for reusing the same image with different repeat offsets, so I don't expect this to change.