I must admit this is not very intuitive. Although the wrapper list @aoa1 and @aoa2 point to different locations in memory the internal array references do not. This can be shown by doing something like this: -

# these will be different
#
print \@aoa1."\n";
print \@aoa2."\n";

# but these won't be!
#
print $aoa1[0]."\n";
print $aoa2[0]."\n";

print $aoa1[1]."\n";
print $aoa2[1]."\n";

print $aoa1[2]."\n";
print $aoa2[2]."\n";
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You can get around this by using a deep clone, i.e.

use strict;
use warnings;
use Storable qw(dclone);
use Data::Dumper;

# define @aoa1 w/ anonymous AoA
#
my @aoa1 = map { [qw(- - -)] } 0..2;  

# deep clone @aoa1 to create @aoa2
#
my @aoa2 = @{dclone(\@aoa1)};

# modify @aoa2
#
$aoa2[1][1] = '@';

# display structures
#
print Dumper(\@aoa1);
print Dumper(\@aoa2);
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Perhaps this information should be added to the Array Tutorial.