An other (bad for memory ?) way :

use YAML;
my $complex_structure;
{
my $complex_structure = Load(Dump($complex_structure));
#Here, $complex_structure is independent
....
}
#Here, you come back to the first $complex_structure
....
[download]

$complex_structure can be quite anything ($ can be replaced with @ or %), and I think it will work even with blessed objects.