Combination packs attract one fee and one charge for each item within the pack, unless it's a combination of different strengths of the same drug.
You can check how many charges combination packs attract by searching for the item in the dictionary of medicines and devices (dm+d). The number of charges will show in the 'Actual Medicinal Product Pack' in the reimbursement information section.
You can view some combination packs and the charges they attract in Part XVI of the Drug Tariff.