|If you are using a USB Mouse you should see both entry's, PS/2 is native to the OS|
Delete BOTH Mouse entry's and reboot, Only the connected Mouse should appear in Device Manager. That is unless you have a program installed that loads the USB (HID Compliant) Mouse Driver.
I'd say, "much ado about nothing".
Check all of Device Manager for problems.
There is nothing to learn from someone who already agrees with you.