The anime adaptation for Ore no Imouto ga Konnani Kawaii Wake ga Nai had two endings, which branched off after episode 11 (the "good end" vs the "true end"). Of course, these couldn't both have happened in the light novels because they aren't consistent with each other. Which one of these follows the light novels closer, i.e. in the novels,
does Kirino go to America or stay in Japan?
I suppose there's also the possibility that these are both anime-original content.