Why are there four different HID Keyboard Devices in Device Manager?

Question

I have one keyboard plugged in, but 4 different HID Keyboard Devices are shown. Why?

Answer 1

Why not? ;-)

Keyboards (or other input devices) use multiple HID devices for various reasons. On keyboards, multiple devices are often used to make N-key rollover possible without relying on better HID support.

Keyboards are not the only type of input device that present themselves as keyboards. Mice also often do, especially if capable of keyboard macros.

For example, consider the following:

From top to bottom, it’s a “Das Keyboard” keyboard, a Logitech MX518 mouse and a Logitech G900 mouse. All of them present a keyboard.

Answer 2

It's also possible that using a KVM switch of some kind can jack up the number of HID instances for various peripherals.

I have two computers, two monitors, one keyboard, and one mouse, but if you look at the picture you will see that Device Manager seems to think otherwise. It all started when I installed a fancy KVM dual monitor solution.

So if you have anything like that in your signal chain, it might be what is doing it.

Answer 3

Contrary to fearofmusic's answer, on my PC, I have determined that a new instance gets created when I plug in the keyboard into a USB port that I hadn’t used for the keyboard before. I can verify this as the device that shows that it is plugged in, changes.