Not sure if I understand what you want to do. But here is my try.
script.pl < path.csv
use strict;
use warnings;
my %h;
while (<>) {
my ( $k, @ips ) = split /\s+/;
$k =~ s/(_.*)$//;
$h{$k}{$_}++ for @ips;
}
for my $srv ( sort keys %h ) {
for ( sort keys %{ $h{$srv} } ) {
printf( "%10s %15s %6s\n", $srv, $_, $h{$srv}{$_} );
}
}
__OUTPUT__
11BT801 10.197.28.38 1
11BT801 10.197.5.82 2
11BT801 10.200.10.10 1
11BT801 10.200.10.11 1
11BT801 10.200.6.42 2
11BT801 10.200.6.50 1
11BT801 10.200.8.26 2
12GT601 10.100.7.14 1
12GT601 10.100.9.16 2
12GT601 10.160.9.16 1
12GT601 10.180.7.13 1
12GT601 10.197.27.36 1
12GT601 10.197.5.82 2
12GT601 10.200.10.10 1
12GT601 10.200.5.40 2