use Data::Dumper;
my $t;
my %a=('c'=> {rr=>$t=[4,5,6], # Notice use of $t for temp store
              ss=>$t});       # which gets assigned HERE ....

print Dumper \%a; 
print qq( $_ = @{$a{c}->{$_}} \n) for qw(rr ss)
---- OUTPUT ---
$VAR1 = {
          'c' => {
                   'ss' => [
                             4,
                             5,
                             6
                           ],
                   'rr' => $VAR1->{'c'}{'ss'}
                 }
        };
 rr = 4 5 6
 ss = 4 5 6