Oh i think you didn't read what these magnetic sensors are used for. I am building a prototype, for a board game, in which positions of the game pieces ( 42 in total) must be detected. And whenever two pieces are in the same square, a robotic arm will activate to judge the challenging pieces and automatically take the losing piece out of the board. I am asking if these magnetic sensors arranged in matrix rather than using MCP23017 to conserve arduino pins can read two occupied positions? Please answer correctly to what is being asked. Thanks.