From what you have posted, I assume you have loaded 2 drivers into the XP-8, you mention 1 is labeled CT-600#1, so the other I guess is labeled CT-600#2.
I believe you have to use 2 RS232 ports on the XP-8, do not use 1 and then try to link the two CT-600's together with their link.
The codes don't change from one to the other, just the port you are sending them out of.
Many here, myself included, have used the 2 way drivers from RTI to control these devices so you shouldn't have issues with the driver commands.
Have you connected to each of the B&K using their set up suite? If you could control each one there you should be OK to control from RTI.
Check your drivers and how you have them set up, confirm your using the right driver (talking to the correct B&K) when assigning a command to a button or macro.
That's all I can think of at the moment.