At customer site, 2 LUN is loaded to server side with multipathing mode from storage side through using Huawei multipathing software UltraPath.
Uninstall UltraPath, reboot server, 2 LUN remains.
Search msiscdsm.sys in the directory of boot disk: \Windows\system32\drivers
If there is msiscdsm, Windows multipathing software is installed; if not, that software is not installed.
Windows iSCSI multipathing software is installed by engineer