How to duplicate screen on a secondary monitor in Phoenix OS?
replace with this command on grub.cfg
(if dual boot with win10 then search how to edit grub.cfg on windows 10)

menuentry 'Phoenix OS--ext display' --class android-x86 {
    insmod part_gpt
    insmod fat
    search --file --set=root /EFI/PhoenixOS/kernel
    linux /EFI/PhoenixOS/kernel quiet root=/dev/ram0 androidboot.hardware=android_x86 SRC=/PhoenixOS vga=788 video=1920x1080 video=eDP-1:d
    initrd /EFI/PhoenixOS/initrd.img


}

where 1920x1080 is my secondary display resolution and eDP is my laptop screen where -1 disable it 
in your case it may be LVDS-1:d try to add both