foreach my $filename (sort keys %mycorpus) {
  my $titles = '';
  my $counter = 0;
    while ($mycorpus{$filename} =~ /title:#(.*?)#\s*$/gm){
      if($counter++){
        last if $counter++; # skip the rest of the matches
        # can also be used to print warnings about multiple titles
        # and check $1 against $titles if they are the same, or not
      }else{
        $titles = $1; # first match, we can store it,
        print  "$titles \n"; # or print it out
      }
      
  }
}