When I used this method to create new rescue mode files for my F23 box (which already had
a rescue mode entry), I got an additional rescue mode entry at the top of the grub menu.
This was fixed by manually editing /boot/grub2/grub.conf to delete the new entry (as
mentioned in
https://ask.fedoraproject.org/en/question/40409/cant-boot-into-rescue-mod...
).