You can add as many RTMeterNeedleIndicator objects to a chart as you want. If they reference the same meter frame they will appear in the same meter.
RTMeterNeedleIndicator meterneedle1 = new RTMeterNeedleIndicator(meterframe1, processVar1);
...
RTMeterNeedleIndicator meterneedle2 = new RTMeterNeedleIndicator(meterframe1, processVar2);
...
RTMeterNeedleIndicator meterneedle3 = new RTMeterNeedleIndicator(meterframe1, processVar3);
...
chartVu.addChartObject(meterneedle1);
chartVu.addChartObject(meterneedle2);
chartVu.addChartObject(meterneedle3);