Can Macao have dual citizenship?

You can't. According to the "Nationality Law of the People's Republic of China", China citizens who have acquired foreign nationality automatically lose their China nationality, and Chinese mainland does not recognize dual nationality. Therefore, in order to acquire China nationality, Macao residents must give up Macao nationality. However, there is an agreement between Macao and Portugal. According to this agreement, Macao residents can enjoy some Portuguese civil rights in Portugal, but this does not mean that Macao residents can own both Macao and Portugal.