//Possible check before hand if we need to do all the following code
NSArray *uniqueSalesCategoryName = [NSSet setWithArray:[finalBarListArray valueForKeyPath:@"sales_sub_category_name"];
if ([uniqueSalesCategoryName count] == [finalBarListArray count])
{
    //There is no need to do the following code, no duplicate.
}

NSMutableArray *barListWithUnicity = [[NSMutableArray alloc] init];
NSMutableDictionary *tempDict = [[NSMutableDictionary alloc] init];
for (BarCodeSKULists *aBarCodeSKULists in finalBarListArray)
{
    NSMutableArray *array = nil;
    array = [keepDict objectForKey:[aBarCodeSKULists sales_sub_category_name]];
    if (!array)
    {
        array = [[NSMutableArray alloc] init];
        [keepDict setObject:array forKey:[aBarCodeSKULists sales_sub_category_name]];
    }
    [array addObject:aBarCodeSKULists];
}
for (NSString *aCategoryName in keepDict)
{
    NSMutableArray *array = keepDict[aCategoryName];
    BarCodeSKULists *barCodeSKUList = [array firstObject];
    if ([array count] > 1) //We have to combine
    {
        [barCodeSKUList combineWithOthers:[array subarrayWithRange:NSMakeRange(1, [array count]-1)]];
    }
    [barListWithUnicity addObject:barCodeSKUList];
}

//Use barListWithUnicity to do what you need


//Method for BarCodeSKUList
-(void)combineWithOthers:(NSArray *)othersBarCodeSKUList
{
    //I assumed there is no check of unicity here, but you can add one if you want
    for (BarCodeSKUList *anotherBarCodeSKUList in othersBarCodeSKUList)
    {
        [[self arrayBarCodeSKUList] addObjectFromArray:[[anotherBarCodeSKUList arrayBarCodeSKUList]];
    }
}