java.lang.IllegalArgumentException: Children: duplicate children added parent=Group@1f95fc4[styleClass=plot-content]
        at javafx.scene.Parent$1.onProposedChange(Unknown Source)
        at com.sun.javafx.collections.VetoableObservableList.add(Unknown Source)
        at com.sun.javafx.collections.ObservableListWrapper.add(Unknown Source)
        at javafx.scene.chart.LineChart.dataItemAdded(Unknown Source)
        at javafx.scene.chart.XYChart.dataItemsChanged(Unknown Source)
        at javafx.scene.chart.XYChart.access$2600(Unknown Source)
        at javafx.scene.chart.XYChart$Series$1.onChanged(Unknown Source)
        at com.sun.javafx.collections.ObservableListWrapper.callObservers(Unknown Source)
        at com.sun.javafx.collections.ObservableListWrapper.add(Unknown Source)
        at com.sun.javafx.collections.ObservableListWrapper.add(Unknown Source)
        at ensemble.samples.charts.line.AdvancedStockLineChartSample.plotTime(AdvancedStockLineChartSample.java:152)
        at ensemble.samples.charts.line.AdvancedStockLineChartSample.access$100(AdvancedStockLineChartSample.java:53)
        at ensemble.samples.charts.line.AdvancedStockLineChartSample$1.handle(AdvancedStockLineChartSample.java:75)
        at ensemble.samples.charts.line.AdvancedStockLineChartSample$1.handle(AdvancedStockLineChartSample.java:70)
        at com.sun.scenario.animation.shared.TimelineClipCore.visitKeyFrame(Unknown Source)
        at com.sun.scenario.animation.shared.TimelineClipCore.playTo(Unknown Source)
        at javafx.animation.Timeline.impl_playTo(Unknown Source)
        at com.sun.scenario.animation.shared.InfiniteClipEnvelope.timePulse(Unknown Source)
        at javafx.animation.Animation.impl_timePulse(Unknown Source)
        at com.sun.scenario.animation.shared.AnimationPulseReceiver.timePulse(Unknown Source)
        at com.sun.scenario.animation.AbstractMasterTimer.timePulseImpl(Unknown Source)
        at com.sun.scenario.animation.AbstractMasterTimer$MainLoop.run(Unknown Source)
        at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(Unknown Source)
        at com.sun.javafx.tk.quantum.QuantumToolkit$8.run(Unknown Source)
        at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
        at com.sun.glass.ui.win.WinApplication.access$100(Unknown Source)
        at com.sun.glass.ui.win.WinApplication$2$1.run(Unknown Source)
        at java.lang.Thread.run(Unknown Source)