1. A method for identifying installed software programs, the method comprising: defining a group comprising computing systems that each have installed software program installations; performing a first scan procedure by scanning one selected computing system of the group of computing systems using a first software signature catalogue to identify installed software programs that are installed on the selected computing system and are identified in the first software signature catalogue; adding software signatures of identified installed software programs identified during the first scan procedure using the first software signature catalogue to a base installation software catalogue, wherein the base installation software catalogue is of a smaller size than the first software signature catalogue; and for each and only remaining computing system in the group of computing systems, performing a second scan procedure by scanning the remaining computing system of the group of computing systems using the base installation software catalogue to identify software programs that are installed on the remaining computing system and are identified in the base installation software catalogue, to identify software programs installed on the remaining computing system and not identified in the base installation software catalogue, and to identify software programs not installed on the remaining computing system and are identified in the base installation software catalogue, thereby the second scan procedure runs faster and at a reduced workload, relative to the first scan procedure, due to the smaller size of the base installation software catalogue.