Looks like a slightly bigger question there than has been answered so far. Consider this:

use warnings;
use strict;

my %codeData;
my $skipping = 0;
my $currCode;

while (<DATA>) {
    if (/^HIT: (\S+)/) {
        $currCode = $1;
        $skipping = exists $codeData{$currCode};
        next;
    }
    
    next if $skipping;
    $codeData{$currCode} .= $_;
}

print $codeData{$_} for keys %codeData;

__DATA__
HIT: code2
stuff for code2
HIT: code3
stuff for code3
HIT: code1
stuff for code1
HIT: code90
stuff for code90
HIT: code2
extra stuff for code2 - ignore this
HIT: code34
stuff for code34
HIT: code90
and extra stuff for code90 - ignore this
[download]

Prints:

stuff for code90
stuff for code3
stuff for code2
stuff for code34
stuff for code1
[download]

Note in particular the use of exists to see if there is an element in the hash already. That frees you to store interesting stuff there rather than an explicit "found it" flag.