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

##</code><code>##

stuff for code90
stuff for code3
stuff for code2
stuff for code34
stuff for code1