Serial Console From Guest To Host

[Solemon]

I am configuring two serial console namely ttyS0 and ttyS1 from guest to host to get the boot and kernel messages on both the console in host,
but i am getting boot/kernel messages on only one console either on ttyS0 or ttyS1.
kernel serial-console documentation says "You can specify multiple console= options on the kernel command line. Output will appear on all of them."

In virtualbox setting,
serial port 1 has been set, as
Port No. COM1
Port Mode - Host Pipe
connect to existing pipe/socked - UNCHECKED
Path/Addess: /tmp/vbox

serial port 2 has been set, as
Port No. COM2
Port Mode - Host Pipe
connect to existing pipe/socked - UNCHECKED
Path/Addess: /tmp/vbox1

i have enable ttyS0 and ttyS1 in guest machine via
# systemctl enable serial-getty@ttyS0.service
# systemctl start serial-getty@ttyS0.service
# systemctl enable serial-getty@ttyS1.service
# systemctl start serial-getty@ttyS1.service


/etc/default/grub
---------------------
GRUB_CMDLINE_LINUX="console=ttyS0,115200n8 console=ttyS1,115200n8 console=tty0 ignore_loglevel"
--------------------
i am getting getty on both the serial console but boot/kernel messages on only one of them ttyS0.
how can i get the boot and kernel messages on both the serial console.?

Host System- ubuntu 16.04
Guest System- ubnutu 16.04