I've never posted to perl monks before. Nor have I ever used Algorithm::Loops, so I'm not exactly sure what is going on. But the Data::Dumper seems to be printing out perfectly correct and expected results. If you take the $VAR1->[0][0][0], etc. to be internal references back into the structure, you can see that it is doing a reference back into itself. And it makes sense: all your tuples in the second $int are the same, except re-grouped, which is exactly what is happening. So as far as I can see things look fine, except, perhaps, you expected new copies of tuples where there aren't any. Mark