First, thanks very much for sharing!
I tried running this in Linux (Mint 17). Instead of seeing two joysticks, I see one with 4-axes. That is, running jstest js0 (there is no js1) gives
Driver version is 2.1.0.
Joystick (Arduino LLC Arduino Leonardo) has 4 axes (X, Y, Z, Rx)
and 7 buttons (BtnX, BtnY, BtnZ, BtnTL, LeftBtn, RightBtn, MiddleBtn).
Testing ... (interrupt to exit)
Axes: 0: 0 1: 0 2: 0 3: 0 Buttons: 0:off 1:off 2:off 3:off 4:off 5:off 6:off
Any ideas?