Hello UI team !!! Here goes bug explanation:

// taken from demo range slider:  http://jqueryui.com/demos/slider/#range

$J("#slider-range").slider({

range: true, min: 0, max: 500, values: [75, 300]

});

// then after

$("#slider-range").slider("destroy")

// still exists inner <div class="ui-slider-range ui-widget-header" style="left: 15%; width: 45%;"/>

Thank you for your work.