USB Key插入和移除监控

近期在做USB Key插入和移除监控，已经做到了插入和移除USB Key时，程序能够及时感应到。

如下为源代码：

private void Form1_Load(object sender, EventArgs e)
{
//创建查询条件，监控USB Key插入和拔出
string condintion = "TargetInstance ISA 'Win32_USBControllerdevice'";
var qCreate = new WqlEventQuery("__InstanceCreationEvent", TimeSpan.FromSeconds(1), condintion);
var qDelete = new WqlEventQuery("__InstanceDeletionEvent", TimeSpan.FromSeconds(1), condintion);

//创建事件查询的侦听器（ManagementEventWatcher）　
var wCreate = new ManagementEventWatcher(qCreate);
var wDelete = new ManagementEventWatcher(qDelete);

 

//事件注册代码
wCreate.EventArrived += (sender1, e1) =>
{
GetInfo(e1.NewEvent);
string msg = "插入USB Key!"; //+ GetInfo(e1.NewEvent);
this.Write(msg);
};
wDelete.EventArrived += (sender1, e1) =>
{
string msg = "拔出USB Key!"; //+ GetInfo(e1.NewEvent);
this.Write(msg);
};

//异步开始侦听
wCreate.Start();
wDelete.Start();
}

用了招行网银USB key和客户提供的USB key测试，运行结果如下：

2013/11/28 0:51:17 插入USB Key!
2013/11/28 0:51:17 插入USB Key!
2013/11/28 0:51:18 拔出USB Key!
2013/11/28 0:51:18 拔出USB Key!
2013/11/28 0:51:20 插入USB Key!
2013/11/28 0:51:21 拔出USB Key!
2013/11/28 0:51:23 插入USB Key!
2013/11/28 0:51:23 插入USB Key!
2013/11/28 0:51:24 拔出USB Key!
2013/11/28 0:51:24 拔出USB Key! 
2013/11/28 0:51:55 插入USB Key!
2013/11/28 0:51:55 插入USB Key! 
2013/11/28 0:51:56 拔出USB Key!
2013/11/28 0:51:56 拔出USB Key!

不解的是，为什么我插入或拔出了一次Key后，程序会捕获到两次事件，在此抛砖引玉，望高手不吝赐教！