Web MIDI Windows backend expects MIDI*CAPS can be a unique identifier to differentiate all connected devices, and usually it's true. When the same device is connected, each device could have a suffix such as (1), (2), ....

But, some devices could have the same CAPS.
Such case, the backend can recognize only the first device. Otherwise, we need to append internal suffix to identify each. However we have no way to bind previously opened device to the one of those devices that have the same CAPS. Thus, even the backend adds an internal suffix, it looks impossible to handle the second device correctly.

Note: We can not identify the opened device by just re-opening to see a result because some device drivers allow to be opened twice.

Possible one idea is
1. close opened device if we have multiple devices that have the same CAPS.
2. identify them with internal suffix, and open each

Downside of this idea is that it needs to stop running I/O if there is, and it could block a bit log time, and the worst fault is this could connect existing JS MIDIPort to a different device at the hotplug event.

Probably this should be a Windows restriction, and could be solved by using WinRT API but it has been blocked by a WinRT API problem.