To Daisychain two or more of these displays you would link CS & CLK to all the displays in parallel and then the tricky part is you need to connect pin 24 of the MAX7219 from the first display to the MOSI of the second display and so on. A bit short sighted of the designers to not break this pin out. As John says your MAX7219 is designed to handle 8x 7 segments so chaining two together you would need to address digits 1,2,3,4 & 9,10,11,12.