sort { 
    $products{'Cat'}{'Pro'}{$a}{'Qua'} <=> $products{'Cat'}{'Pro'}{$b}{'Qua'}
        ||
    $a cmp $b
}
keys %{ $products{'Cat'}{'Pro'} }

##</code><code>##

my $pro_products = $products{Cat}{Pro};

sort { 
    $pro_products->{$a}{Qua} <=> $pro_products->{$b}{Qua}
        ||
    $a cmp $b
}
keys %$pro_products