为什么我会收到两个本地通知的警报?

    NSLog(@"Configuring notifications time is up.");
    noTimeLeft=[[UILocalNotification alloc]init];
    noTimeLeft.fireDate=meterEndTime;
    noTimeLeft.alertBody=@"Your parking meter has expired!";
    noTimeLeft.alertAction=@"Go to meter";
    noTimeLeft.userInfo=[NSDictionary dictionaryWithObject:self.meterEndTime forKey:@"NSDate"];
    [[UIApplication sharedApplication] scheduleLocalNotification:noTimeLeft];
    NSLog(@"Configuring notifications finished time is up.");