#!/usr/bin/env perl

use strict;
use warnings;
use constant {
    REC_SEP => "\n//\n",
    KEY_SEP => "\t",
    OUT_FMT => "%s\n%s\n%s\n//\n",
};

my %uniq;

{
    local $/ = REC_SEP;

    while (<DATA>) {
        chomp;
        my ($id, $s1, $s2) = split;
        $uniq{join KEY_SEP, $s1, $s2} = $id;
    }
}

printf OUT_FMT, $uniq{$_}, split(KEY_SEP) for keys %uniq;

__DATA__
nick
AAAAAAAAAA
BBBBBBBBBB
//
george
EGRGERHTETEHTHR
VFRTTHTRRHTE
//
andreas
AAAAAAAAAA
BBBBBBBBBB
//
thomas
EWTRYTUYJTHT
CEWWEQRWT$G
//
peter
EGRGERHTETEHTHR
VFRTTHTRRHTE
//

##</code><code>##

andreas
AAAAAAAAAA
BBBBBBBBBB
//
peter
EGRGERHTETEHTHR
VFRTTHTRRHTE
//
thomas
EWTRYTUYJTHT
CEWWEQRWT$G
//

##</code><code>##

... for sort { $uniq{$a} cmp $uniq{$b} } keys %uniq;