each “r#” channel is one DMX universe. you can send r0~r7 to 192.168.1.208 and then send r8~r15 to 192.168.1.209
What I’m not sure is: does your second arduino expect to see universe numbers 0,1,2,3,4,5,6,7 or does it expect to see universe numbers 8,9,10,11,12,13,14,15? That depends on your Arduino code, I can not tell how you have that part working on the Arduino side.
Since the second Arduino is a different IP address, you CAN send it’s set of TouchDesigner channels (r8, r9, r10, r11, r12, r13, r14, r15) to the Arduino with the same universe numbers (0, 1, 2, 3, 4, 5, 6, 7)
or different universe numbers (8, 9, 10, 11, 12, 13, 14, 15) if you need to (for coding reasons) but that’s up to you.
Either way, you can just keep adding rows to the bottom of that Table DAT (right click on the last row number when the DAT is in “active” mode and click “Add Below”) and route more TocuhDesigner channels to more DMX universes / IP addresses - as many as you want. And the performance might be better going through a single DMXout CHOP.