Madam Rajni Mathur
There are feeble or rarest chances to have a same birth chart for two persons. The conditions are they should be at the same place, at the same time.
In vedic astrology the rasi and navamsa would become same. But if you take about twins, all the positions would be the same. But there would be slight difference in their features or professions. One may like his father and other may like his mother. That is why Prof. K.S.Krishna Murthi made research and developed the system known as KP system.
In KP system he used Placidus divisions for bhava charts and made divisions of the constellations as per Vimsottari Division. He developed sub lord theory. The sub lord is the lord of the subdivision in the bhava chart. He is the deciding factor. With this he proved that in twins, one child became a surgeon while another became a veterinary doctor. He proved that the 10th cusp sub lord is Jupiter who made a surgeon to one child and another had Saturn to become veterinary doctor. That is subtle difference to give various professions.
If you are interested please go through his readers to clarify your doubts.
Good Luck
JVS Rao (KP follower)