I encountered this question in a quiz and got it wrong:
"Manon aime une autre personne." means:
Maybe I'm splitting hairs here, or the translation isn't quite literal in English, but the correct answer "Manon loves another person" seems to imply something different. I read this as "Manon loves [a different] person." To say that Manon loves another person implies to me that she may love more than one person. For example, if I said "J'ai une autre voiture," am I saying I have 2 cars now, or that I have a different/new car?