Your problem description was not exact. You didn't tell and the example data didn't tell either whether multiple event id's can follow one code id. You once used plural for event ids and in another sentence you used the singular.

If only one event id can follow one code id, I thought I'd skip the multiple reading of file2. Instead using a lookup table I would parse the valid code id's in advance.

#! /usr/bin/perl

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

# State machine
use constant CODE  => 'CODE';
use constant EVENT => 'EVENT';

# Codes pre-parsed from file1
my %codes = (
    12131 => 1,
    34234 => 1,
    53435 => 1,
    46566 => 1,
    34522 => 1,
);

my %results;
my ($code_id, $event_id);

my $state    = 'CODE';
my $re_code  = qr{Code \s+ id \s+ -(\d+)- }x;
my $re_event = qr{Event \s+ id \s+ (-\d+-) }x;

LINE:
while( <DATA> ) {

    chomp();

    if( ($state eq CODE) && /$re_code/ ) {
        # Check that code is valid
        if( $codes{$1} ) {
            $code_id = $1;            
            $state   = EVENT;
        } else {            
            next LINE;
        }
    } else {
        if( ($state eq EVENT) && /$re_event/ ) {
            $results{$code_id} = $1;
            $state = CODE;
        } else {            
            next LINE;
        }        
    }
}

print Dumper(\%results);

1;

__DATA__
some content
some content
some content
some content
some content
blah. blah.
Code id -46566-
some content
some content
some content
some content
Event id -445778441211-
some content
some content
some content
some content
some content
some content
some content
Code id -12131-
some content
some content
some content
some content
some content
some content
some content
some content
some content
Event id -123443111131-
Code id -12342-
some content
some content
some content
some content
some content
some content
some content
some content
Event id -445987432141-
[download]

Output:

$VAR1 = {
          '12131' => '-123443111131-',
          '46566' => '-445778441211-'
        };
[download]

Update: removed the odd __DATA2__ tag from the end..