or alternately (selectable in Options),
* Analog Joystick #1 and Digital Joystick #2
That feature is intended for people who own one digital stick, and one analogue stick (rather than two digital ones). In the "analog" mode, Digital Joystick #1 is not used (because it's its button inputs would conflict with Analog Joystick #1).
Disassembly of the joystick code in Tennis Cup 2: