在ASP.NET中使用单身的正确方法？

Question

问题：以下代码是否100％确保每个用户的对象的唯一性（根据我的理解，这意味着每个浏览器（或请求））？

/// <summary>
        /// Ensures the uniqueness for each request. 
        /// </summary>
        private static MultiLanguageProvider Instance
        {
            get
            {
                var currentSession = HttpContext.Current.Session;
                var nameOfInstance = nameof(MultiLanguageProvider);

                if ((currentSession[nameOfInstance] as MultiLanguageProvider).IsNull())
                    currentSession[nameOfInstance] = new MultiLanguageProvider();

                return currentSession[nameOfInstance] as MultiLanguageProvider;
            }
        }