"same as mailing address checkbox" how to get the value?

I currently have a checkbox for "same as mailing address" option whereby if checked, the values on the left will populate the values on the right. However, 2 of the options are dropdown list boxes (state, county) options that I need to get the value of each out of the left side of the form, and then copy these 2 values over to the right side of the form i.e, "same as mailing address" drop down list boxes. Each side of the form has the same 2 components - identical dropdown listboxes for state and country that I need to auto-populate to the right side? XRM.PAGE has offered numerous solutions that for whatever reason in 2011 fail ??