Actually, Constância is a legitimate name in Brazil. It's a bit old-fashioned, but it's definitely used here. Constança isn't used much here - that name is more of a European Portuguese name.
One Portuguese Queen was called Constancia. She was wedded to D. Pedro I, who was in love with D. Inês de Castro. As Constancia died, Pedro secretly got married to D. Inês who had three kids. Later on D. Inês was murdered by three men who were following the king's orders (D. Pedro's father.)