#!/usr/bin/perl

use strict;
use warnings;
use Data::Dumper;

my %hash;

while (<DATA>) {
    (my $key, my $value) = /(\S+\s+\S+)\s+(\S+\s+\S+)/;

    $value = join ":", split " ", $value;
    $hash{$key} .= ", " if exists $hash{$key};
    $hash{$key} .= $value;
}

print "$_ $hash{$_}\n" for sort keys %hash;

__DATA__
id1    name1 cat1  catname1
id1    name1 cat2  catname2
id2    name2 cat3  catname3
id3    name3 cat1  catname1
id3    name3 cat4  catname4

##</code><code>##

id1    name1 cat1:catname1, cat2:catname2
id2    name2 cat3:catname3
id3    name3 cat1:catname1, cat4:catname4