use warnings;
use strict;

use Data::Dumper;

# store codes in hash for fast lookup
my %code;
{
    open(my $FH1, "<", "file1") or die($!);
    chomp() and ++$code{$_} while <$FH1>;
}

# read in chunks that end with 'Code id -'
my %data;
{
    local $/ = "Code id -";

    open(my $FH2, "<", "file2") or die($!);

    while (<$FH2>)
    {
        /^(\d+)-.*\nEvent id -(\d+)-/s or next;
        $data{$1} = $2 if $code{$1};
    }
}

print Dumper(\%data);

__END__
$VAR1 = {
          '12131' => '123443111131',
          '46566' => '445778441211'
        };
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