• fix: a fallback language whose formatted code is already in the hierarchy is no longer added a second time. toResolveHierarchy() checked the raw fallbackLng value against the list, but the list holds formatted codes, so any fallback written differently from its formatted form slipped through: lng: 'de-CH' with fallbackLng: 'de-ch' gave languages ['de-CH', 'de', 'de-CH'], and the same happened with fallbackLng: 'EN' + cleanCode, lowerCaseLng, and Intl aliases (iw-IL → he-IL). Missing keys were looked up in the same language twice. Only exact duplicates are removed; the order is unchanged. Thanks @lprnmns (#2450).