use List::MoreUtils 'uniq';
use Data::Dumper;

my $aref = [ 1, 2 ];
my @aref_duplicated = ( $aref, $aref, $aref );

my @u1 = uniq( @aref_duplicated );
my @u2 = keys %{{map {$_=>1} @aref_duplicated}};
print Data::Dumper->Dump( [ \@u1,         \@u2         ],
                          [ '*from_uniq', '*from_keys' ] );
__END__
@from_uniq = ( 
               [ 
                 1,
                 2
               ]
             );
@from_keys = ( 
               'ARRAY(0x8153c28)'
             );