Exception in thread "JavaFX Application Thread" java.lang.IllegalArgumentExcepti
on: Duplicate category ; New category 1 already present
        at javafx.scene.chart.CategoryAxis.checkAndRemoveDuplicates(CategoryAxis
.java:216)
        at javafx.scene.chart.CategoryAxis.lambda$new$565(CategoryAxis.java:82)
        at com.sun.javafx.collections.ListListenerHelper$Generic.fireValueChange
dEvent(ListListenerHelper.java:329)
        at com.sun.javafx.collections.ListListenerHelper.fireValueChangedEvent(L
istListenerHelper.java:73)
        at javafx.collections.ObservableListBase.fireChange(ObservableListBase.j
ava:233)
        at javafx.collections.ListChangeBuilder.commit(ListChangeBuilder.java:48
2)
        at javafx.collections.ListChangeBuilder.endChange(ListChangeBuilder.java
:541)
        at javafx.collections.ObservableListBase.endChange(ObservableListBase.ja
va:205)
        at javafx.collections.ModifiableObservableListBase.add(ModifiableObserva
bleListBase.java:155)
        at ensemble.samplepage.XYDataVisualizer.insertItem(XYDataVisualizer.java
:369)
        at ensemble.samplepage.XYDataVisualizer.lambda$new$62(XYDataVisualizer.j
ava:232)
        at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(Comp
ositeEventHandler.java:86)
        at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventH
andlerManager.java:238)
        at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventH
andlerManager.java:191)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDis
patcher.java:58)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispat
chChainImpl.java:114)
        at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
        at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
        at javafx.event.Event.fireEvent(Event.java:198)
        at javafx.scene.control.MenuItem.fire(MenuItem.java:462)
        at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContaine
r.doSelect(ContextMenuContent.java:1405)
        at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContaine
r.lambda$createChildren$343(ContextMenuContent.java:1358)
        at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.h
andleBubblingEvent(CompositeEventHandler.java:218)
        at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(Comp
ositeEventHandler.java:80)
        at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventH
andlerManager.java:238)
        at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventH
andlerManager.java:191)
        at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(C
ompositeEventDispatcher.java:59)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDis
patcher.java:58)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispat
chChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDis
patcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispat
chChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDis
patcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispat
chChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDis
patcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispat
chChainImpl.java:114)
        at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
        at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
        at javafx.event.Event.fireEvent(Event.java:198)
        at javafx.scene.Scene$MouseHandler.process(Scene.java:3757)
        at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485)
        at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
        at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
        at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotificatio
n.run(GlassViewEventHandler.java:394)
        at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotificatio
n.run(GlassViewEventHandler.java:295)
        at java.security.AccessController.doPrivileged(Native Method)
        at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEve
nt$353(GlassViewEventHandler.java:432)
        at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(Quantum
Toolkit.java:389)
        at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(Glas
sViewEventHandler.java:431)
        at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
        at com.sun.glass.ui.View.notifyMouse(View.java:937)
        at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
        at com.sun.glass.ui.win.WinApplication.lambda$null$147(WinApplication.ja
va:177)
        at java.lang.Thread.run(Thread.java:748)