双击wpf中treeview控件的子项后Expanded或MouseDoubleClick会执行两次TreeViewItem_MouseDoubleClick或TreeViewItem_Expanded如何解决我双击子项时执行两次的问题

`<TreeView
         x:Name="Tree_Channel"
         ItemsSource="{Binding TreeItems}">
        <TreeView.ItemContainerStyle>
         <Style TargetType="{x:Type TreeViewItem}">
         <EventSetter Event="Expanded" Handler="TreeViewItem_Expanded" />
         <EventSetter Event="PreviewMouseDoubleClick"  Handler="TreeViewItem_MouseDoubleClick"/>
            </Style>
        </TreeView.ItemContainerStyle>
        <TreeView.ItemTemplate>
        <HierarchicalDataTemplate ItemsSource="{Binding Children}">
        <TextBlock Text="{Binding Name}" />
         </HierarchicalDataTemplate>
        </TreeView.ItemTemplate>
    </TreeView>

  public Window1()
        {
     InitializeComponent();
    DataContext = this;

        TreeItems = new ObservableCollection<TreeNode>();

        var rootNode1 = new TreeNode("Root 1");
        var rootNode2 = new TreeNode("Root 2");     
        rootNode1.Children.Add(new TreeNode("Child 1"));
        rootNode1.Children.Add(new TreeNode("Child 2"));
        rootNode2.Children.Add(new TreeNode("Child 3"));
        rootNode2.Children.Add(new TreeNode("Child 4"));     
        TreeItems.Add(rootNode1);
        TreeItems.Add(rootNode2);
    }
    public ObservableCollection<TreeNode> TreeItems { get; set; }
    private void TreeViewItem_Expanded(object sender, RoutedEventArgs e)
    {

    }  
    public class TreeNode

    {
        public string Name { get; set; }
        public ObservableCollection<TreeNode> Children { get; set; }

        public TreeNode(string name)
        {
            Name = name;
            Children = new ObservableCollection<TreeNode>();
        }
    }

    private void TreeViewItem_MouseDoubleClick(object sender, MouseButtonEventArgs e)
    {

    }
    }

字符串