#!/usr/bin/env perl -l

use strict;
use warnings;

my (%data, %seen, @order);

while (<DATA>) {
    s/\s*#.*$//;
    next if /^\s*$/;
    my ($key, @rest) = split;
    push @order, $key unless $seen{$key}++;
    push @{$data{$key}}, grep { ! $seen{$_}++ } @rest;
}

print join ' ', $_, @{$data{$_}} for @order;

__DATA__
127.0.0.1 c2.gostats.com #SpySweeper.Spy.Cookie

127.0.0.1 ads.goyk.com

# 1-800-hostingAS3321069.41.160.0 - 69.41.191.255

127.0.0.1 2a02:598:2::1095
127.0.0.2 2a02:598:2::1096
 
127.0.0.2 2a02:598:2::1096
127.0.0.2 2a02:598:2::1096 127.0.0.2