First i would like to tell some information about my setting here:
1. i set Weight Class Kilogram(s) as default
2. i set Currency MYM (Malaysia Ringgit) as default
3. in zone shipping module i set Cost as: 10:12 , that mean 0 - 10 kg item will be charge in MYM12.
4. when i try buy 1 item with weight 5kg, in zone Shipping Method it will show as MYM12.
my question is, is that possible can make it when i buy 2 item (total weight less than 10kg), the zone shipping method will show as MYM24

The courier service i use their charger is : First 10kg - MYM12 / additional 1kg - MYM2 / all count with per parcel not in total weight.....
sorry for not good in english...... hope you can understand what i mean.... thank you.
