file size in add remove programs

Does anyone knows why squackbox fsnavigator and other fs related programs they show the same file size as FS2002 I attach an example like Bota mision to the moon which shows a size of 2.1 gigs which in fact is about 15 megs. It is showing the same size as FS2002. Can it be because they are install directly into FS folder?More dramatically is that the hardisk is showing a size that's not true.My total file size won't exceed 4gigs and because of the double up of the programs above the partition is showing in excess of 7 gigs is used??????