If you have a Dell laptop and a Dell monitor that both have webcams, they show up as identical in the hardware list so Teams does not identify them as separate devices.

In this case we have a Dell Latitude 7400 with a webcam and with two Dell P2418HZm monitors that also each has a webcam. All 3 cameras show up in device manager as separate cameras with identical names: "Integrated Webcam". When you pull up the Device panel in Teams, it only shows the first device with the name "Integrated Webcam".

Teams version is 1.3.00.19173