So today I installed Ubuntu 16.04.1 as my second OS, Windows 10 being the first one. After the successful installation I came to cleaning some options in BIOS, and I've seen that Ubuntu pops up twice in the boot options section. Both of them do generally the same when overridden, they go into GRUB. So why there are two of them, and why even if deleted they can be seen again after full reboot? Can I do something about it, and is something worthy to worry about?
sudo efibootmgr -v in an Ubuntu Terminal window to view all your EFI entries in detail. Chances are the two
ubuntu entries will differ, in that one will boot
shimx64.efi and the other will boot
grubx64.efi. If Secure Boot is disabled on your computer, both entries will work; but if you enable Secure Boot, chances are only the
shimx64.efi entry will work. I don't know why Ubuntu registers both entries, since the
shimx64.efi entry should work whether Secure Boot is enabled or not.
In principle, you could remove one entry with
efibootmgr -b #### -B, where
#### is the hexadecimal number associated with the entry you want to delete. I've seen reports of Ubuntu adding these entries back, but I've never looked into the issue in any detail.
In the end, having two
ubuntu entries is harmless. At worst, it's a bit of extra clutter when you use the firmware's boot manager or need to adjust entries with
efibootmgr or similar tools.