Here is an example with one interface D1024

And here is an example with two interfaces D1024

"1 (D1024)" means the first interface
The first line from the top is always the first DMX output of the interface.
The second line from the top is always the second DMX output of the interface.
"2 (D1024)" means the second interface
That said, please note that using the option "
Change defaut DMX universes mapping" is not mandatory. You can leave it unchecked, let the computer decide the interfaces order and plug your DMX lines according to the default DMX lines setup.