Is it permissible to pray that Allah bless me with a wife in Paradise who is an exact replica of a specific girl who is currently engaged?

If someone else proposes to the woman you admire, the correct approach is to turn away from her and seek another righteous woman, and supplicate to Allah to grant you success in choosing a righteous wife. A wise person should occupy himself with what brings him closer to Allah and leads him to His pleasure and entry into His Gardens. For in Paradise, "They will have therein whatever they desire, and with Us is more."