奇怪的问题：db.tbLog.Add(log)竟然被覆盖了

            tbLog log = new tbLog();
            log.Operator_name = "test";
            //1会员，2服务中心，3管理员
            log.Operator_Type = "管理员";
            log.DateTime = DateTime.Now;
            log.IP = GetClientIPOrAdd.GetIP();
            log.Operation = "ExecuteSqlCommand时间：" + a;
            db.tbLog.Add(log);
            
            tbLog log1 = log;
            log1.Operation = "EF时间：" + b;
            db.tbLog.Add(log1);

            db.SaveChanges();