I was attempting to promote one of my factions members, by doing /f admin [name], and as soon as the command had been done: it made that player leader. And as far am I'm aware, an admin is not the owner/leader. Luckily, the player was loyal and we managed to sort it out.
As far as I know only the owner can be an **admin and the next rank is a *moderator which can basically do everything an admin can do so this isn't a glitch/bug. Hope this helps!