There are 2 fire bottles in each compartment. The ECAM checklist would have required the crew to fire both bottles.
Just a clarification to the previous post. There are two fire bottles total for the cargo compartments that can be either discharged into the forward or aft/bulk cargo compartments. A fire extinguishing button for the forward or aft/bulk will automatically discharge both bottle into the respective compartment. Once the bottles have been discharged they are no longer available for the other compartment if god for bid you had a second cargo smoke warning in that second compartment.