Your selectors are fine, but your error in the first declaration:
background-image: url(img/logo/divide.jpg) no-repeat left center, url(img/logo/divide.jpg) no-repeat right center;
You need to use a shorthand property backgroundinstead background-image, because you specify a bunch of other values along with the images. The reason your second rule seems to override the first is because the first rule is invalid and therefore actually ignored altogether.
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