use Data::Dumper;

my $in = '0000       21 20 20 20 20 20 20 20 36        !       6';
my @out = split /\s{2,}/, $in, 3;
print Dumper \@out;
__END__
$VAR1 = [
          '0000',
          '21 20 20 20 20 20 20 20 36',
          '!       6'
        ];