WIN10-64: How to determine occupied COM port

The device manager image below shows that devices occupy com ports 4,5,6 & 7. Attempts to move the device from 7 to 13 failed because 13 was allegedly occupied. Reboot did not resolve this problem. Why is 13 marked as occupied only in the UI to change the port setting and not the list of devices?

http://i.stack.imgur.com/4nYQB.jpg

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