This was a problem that pestered us in many an AYA translation, until today when, after translating thirteen whole volumes, we finally hit upon the idea of making a chapter list to refer to, so we don't accidentally repeat a title in the future.
So, after going through and listing one-hundred and eleven chapter titles (plus a few special chapter titles, counted separately), we found out that Kou Fumizuki has yet to repeat a single title, even when he has two different chapters whose titles could be translated to, for example, "friends." Eheh. We on the other hand, have two chapters entitled "Friends," (at least we can say that one is "Houyuu--Friends," and the other is "Tomogaki--Friends"). But aside from that, we actually managed to follow Fumizuki-sensei's lead and not repeat anything. Yay!