Having both kernels in grub is normal. You can edit grub and comment the .31 out or switch .32 to default, or leave it alone your choice.
If you run "equo search virtualbox" you will see the drivers you need are kernel dependent and you will need to install the correct drivers for the .32 kernel, same as your video card, nvidia drivers for a .31 kernel will not work with .32
Not sure why the update did not finish and install the kernel the first time. Same thing happened to me, I lost video and when I re-installed them, pulled in .32