Radio buttons triggering an AJAX callback to load form elements are pre-selected after navigating back to form in browser
OK after a bit of searching I found this: http://codekarate.com/blog/drupal-7-prevent-duplicating-javascript-behaviors

Specifically it mentions Drupal 7 integrates the Jquery Once plugin into Drupal 7 core.

Therefore I can modify my Drupal.behaviours.attach to the following:

  Drupal.behaviors.uncheckRadioButtons = {
    attach : function(context, settings) {
      $('body').once('deselect_radios', function (){
        $('input[type="radio"]:checked').attr('checked', false);
      });
    }
  };