Comment 36 for bug 1466150

Since focal the change I originally asked for at the beginning of this thread has now been made. If you set up multi efi partitions, not raided, when you run "dpkg-reconfigure grub-efi-amd64" the system asks which efi partitions you wish to use. You can specify more than one and it then installs to each of them. It remembers the choice next time grub is updated via apt.