As dave_the_m points out, you're not dereferencing quite properly. Whenever I get output that doesn't match what I think it should, I always (always always) resort to Data::Dumper. Add something like this to your code:

  use Data::Dumper;
  print Dumper($mctest);
[download]

You'll see that it's not an array of arrays very quickly this way. And that should lead you to suspect you're using it incorrectly. You may still have the question of how to dereference incorrectly, but at least it'll be the right question. :-)

Data::Dumper has given me many a forehead-slapping "d'oh!" moment. Why? Because it has already had all the derefencing bugs worked out. It just works. My code generally isn't quite so reliable. :-)