The difference in the action of IgnoreHWSerNum of USB2.0 and USB3.0

Question

I googled around a lot but was unable to find an answer to this problem, So I am putting it here.
I simply want that for a USB port, the assigned COM port number does not change for devices with a different serial numbers.
On investigating I found out that by configuring IgnoreHWSerNum Key in the Registry, registration of Serial Numbers for a device can be ignored.
Hence I set the IgnoreHWSerNum in the following Registry Key:
  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\usbflags
To Test I inserted one of the device in the USB 2.0 port.
The device was detected as COM3
Then I tried an another simillar device with different serial number in the same port.
I could confirm that this one was also detected as COM3
On checking the entries corresponding to "Vendor ID" and "Product ID" in the following Registry Key
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\USB
.. I cannot find the serial numbers of the devices, which is obvious.
But when I try these two devices in a USB 3.0 port I get different COM port number for each.
1st device: COM5
2nd device: COM7
On checking the entries corresponding to "Vendor ID" and "Product ID" in the following Registry Key
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\USB
... I find the devices serial number, which means that the IgnoreHWSerNum entry did not work.
Does it mean that IgnoreHWSerNum registry settings does not work for USB 3.0? Or is there another place for the settings?
If not then how can I assign fixed COM port numbers to the devices with different serial numbers for USB 3.0?
Any help is appreciated!

Answer 1

I am seeing the same behavior as mentioned by mr.p-funk.
I am setting IgnoreHWSerNumXXXXYYYY = 1 in the Registry for a specific printer model (VID=XXXX, PID=YYYY).
When each printer of the SAME model is connected to the same USB2.0 port, the "ignore serial number" works as expected,
(i.e. multiple printers of the SAME model can be connected to the SAME physical USB port on the PC without creating a different "print queue".)
However, when connecting the 2 printers to a USB3.0 port, it does NOT work. Instead, it behaves as though IgnoreHWSerNumXXXXYYYY
in Registry is set to 0 instead of 1. (i.e. each printer of the SAME model gets a NEW print queue when connected to the SAME USB port on the PC.)
I work for a printer manufacturer, and being able to "Ignore the USB Serial Number" is something we use with customers quite often.
So, if there is a way to make this work when the printer is connected to a USB3.0 port on the PC, we need to know about it.
Sorry Alex Zhaozx, but Kate Li's response is NOT the answer to the question. She only describes the behavior a user will see when this Registry setting (=1) is working correctly,
i.e. with a USB2 port. We are asking about HOW to make it work with a physical USB3.0 port on the PC.