yes as soon as I get the second circuit working I will be trying your code with the two matrices connected together, but until then I still have this hardware problem,
Is it a hardware problem? you say it displays a couple of characters okay using one piece of code but with a different bit of code it displays just one character then nothing. The ScrollTest2 code should also work fine with a single MAX7219 chip, how does that look if you upload it to the arduino connected to the breadboard matrix.
Do you have both capacitors on the MAX7219 chip and a suitable IREF resistor value for your particular type of LED's