cloneNode and dynamic forms with javaScript

When I clone a fieldset node (fieldsets are awesome) that contains radio buttons, the radio button selection from the node cloned (the clone-ee?) is lost. To see this behavior, select a pet type under both cloneNode and createElement below, and then click both Add Pet buttons. In Firefox, the cloneNode form loses your radio button selection immediately, and in IE it treats all the radio buttons as if they were part of the same set. The createElement version works fine.

To get around this issue, I created a version that creates a blank fieldset element and then creates the radio button elements as innerHTML. I feel like there must be a better solution—it's not so bad on this example fieldset, with just 3 elements, but on a larger fieldset it quickly becomes unwieldy. Not to mention the code would have to be maintained in 2 places on the page instead of one.