Apply 2 background images to one element at the same time

[Carl Shore]

Is there a way that retina.js can be updated to include support for multiple background images with positioning, e.g. to provide a retina alternative to the following?

background: url(/images/icons/QA_BLUE.png) center 15px no-repeat, url(/images/icons/GREEN-PLUS-ICON-RGB.png) 20px 20px no-repeat;

Thanks.