diff --git a/device/win_usb/win_usb.cpp b/device/win_usb/win_usb.cpp
index c3f996f..3521bdf 100644
--- a/device/win_usb/win_usb.cpp
+++ b/device/win_usb/win_usb.cpp
@@ -886,8 +886,8 @@ void usb_monitor::register_monitor_wnd(const wchar_t* cls)
 void usb_monitor::notify_usb_event(usb_device*& dev, bool arrive)
 {
     std::lock_guard<std::mutex> lock(lock_);
-    int ev = arrive ? LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED : LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT;
-    DEVID id = dev->id();
+    int     ev = arrive ? LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED : LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT;
+    DEVID   id = dev->id();
 
     if (arrive)
     {
@@ -896,12 +896,20 @@ void usb_monitor::notify_usb_event(usb_device*& dev, bool arrive)
         {
             if (devices_[i]->id() == id)
             {
-                dev->release();
-                dev = devices_[i];
-                dev->add_ref();
-                dev->set_online(true);
-                found = true;
-                break;
+                if (devices_[i]->is_online())
+                {
+                    VLOG_MINI_1(LOG_LEVEL_DEBUG_INFO, "%s is already in device queue and received ARRIVE again, discard this event.\n", dev->name().c_str());
+                    dev->release();
+                    return;
+                }
+                else
+                {
+                    dev = devices_[i];
+                    dev->add_ref();
+                    dev->set_online(true);
+                    found = true;
+                    break;
+                }
             }
         }
         if (!found)
@@ -922,7 +930,14 @@ void usb_monitor::notify_usb_event(usb_device*& dev, bool arrive)
             dev->add_ref();
             if (dev->is_open())
             {
-                dev->set_online(false);
+                if (dev->is_online())
+                    dev->set_online(false);
+                else
+                {
+                    VLOG_MINI_1(LOG_LEVEL_DEBUG_INFO, "%s is already offline and received LEAVE again, discard this event.\n", dev->name().c_str());
+                    dev->release();
+                    return;
+                }
             }
             else
             {
@@ -953,6 +968,8 @@ int usb_monitor::on_usb_pnp(WPARAM wp, LPARAM lp)
 	if (wp == DBT_DEVICEQUERYREMOVE)
 		return cur_dev_name_ != u2utf8(dev->dbcc_name);
 
+    VLOG_MINI_2(LOG_LEVEL_DEBUG_INFO, "event '%08x' of device %s\n", wp, u2utf8(dev->dbcc_name).c_str());
+
     usb_device* ud = new usb_device(u2utf8(dev->dbcc_name).c_str());
     *ud = dev->dbcc_classguid;
 	if (!PostThreadMessageW(handle_msg_id_, MSG_DEVICE_PNP, wp == DBT_DEVICEARRIVAL, (LPARAM)ud))