can anyone else get the Wiki (RS232) link to work?

Is it possible to connect two of those shields on one Arduino MEGA 2560? I would like to read some data from one RS232 port, modify it on Arduino and then send data to another RS232 port.

Is this compatible with the Arduino Due? Would there be any issues operating this at the chip's max rate of 1Mbps?

The 5VDC is the working voltage for Arduino, the voltage of RS232 should be 8-12V.