I would like to create an HighStock chart containing a navigator component displaying multiple series, being the same series displayed in the main graph. It seems that this
Multiple series in navigator are not oficially supported, so only this "hack" which you use display multiply series in navigator. Example: http://jsfiddle.net/6fFwM/ This feature is requested in our system here (http://highcharts.uservoice.com/forums/55896-general/suggestions/2361925-allow-navigator-to-have-multiple-data-series), so you can vote for it.
window.chart.addSeries({
name : "",
xAxis: 0,
yAxis: 1,
type: "line",
enableMouseTracking: false,
data : new_data,
showInLegend:false
});