Is it possible to turn on/off two layers at once with the openlayers_plus module?
I think the best way to do this would be to create a function that uses setVisibility()

For example (without toggle logic):

$('.my-button').click(function(e) {
  e.preventDefault();
  var ol = $('.openlayers-map').data('openlayers');
  ol.openlayers.getLayersByName('myLayerName1')[0].setVisibility(false);
  ol.openlayers.getLayersByName('myLayerName2')[0].setVisibility(false);
});