Solution:

In our new BIOS (version 2.10), it reports two I/O ranges for each COM ports because the UMC chipset (UM8669F) can not decode I/O address lines correctly. For UM8669F Rev.A and B, address line A10 is not decoded so BIOS must reports one more I/O address to avoid I/O conflicting problem. For UM8669F Rev.C, this problem is solved so BIOS will report 1 I/O range only. The same phenomena happens on floppy drive controller and parallep port, too. However, it will not affect the functions of serial ports nor parallel port.