Amoreirinha, 28, played for Benfica between 2004 and 2007 and last represented Portuguese Ist division side Vitoria Setubal, while 30-year-old Machado is a product of the Sporting Lisbon Academy.
Machado is also believed to have played with Real Madrid Portuguese star footballer Cristiano Ronaldo and the likes of Quaresma, Carlos Martins and Moutinho.
Churchill Brothers have now confirmed three of their four foreigners for the 2013-14 season, with Gabon striker Henri Antchouet being already retained.
"We are very happy to join the champion club of India and moreover to move to a place like Goa was a dream, especially with the close ties between Goa and Portugal," the duo said.
The signings were facilitated by their agent Raul Fernandes, who had also brought Antchouet to the Goan club.