Comment 3 for bug 118384

I can confirm and reproduce the bug. I have an Arduino Leonardo, and I have tried to run on it the code in
http://arduino.cc/forum/index.php/topic,134108.0.html
Namely, the code lets you hook up the Leonardo to two old-school Atari joysticks, and have them appear as two USB joysticks. I only get js0 on /dev/input. When running jscal js0 I get

Joystick has 4 axes and 4 buttons.
Correction for axis 0 is broken line, precision is 0.
Coeficients are: 0, 0, 536870912, 536870912
Correction for axis 1 is broken line, precision is 0.
Coeficients are: 0, 0, 536870912, 536870912
Correction for axis 2 is broken line, precision is 0.
Coeficients are: 0, 0, 536870912, 536870912
Correction for axis 3 is broken line, precision is 0.
Coeficients are: 0, 0, 536870912, 536870912

After commenting out the bit after "// Commodore / Atari Joystick 2", I get
Joystick has 2 axes and 2 buttons.
Correction for axis 0 is broken line, precision is 0.
Coeficients are: 0, 0, 536870912, 536870912
Correction for axis 1 is broken line, precision is 0.
Coeficients are: 0, 0, 536870912, 536870912

So, Ubuntu has merged the two joysticks into one with double the axes and double the buttons.
"cat /etc/lsb-release" gives
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=12.04
DISTRIB_CODENAME=precise
DISTRIB_DESCRIPTION="Ubuntu 12.04.2 LTS"

"uname -a" gives
Linux abuyoav 3.2.0-40-generic #64-Ubuntu SMP Mon Mar 25 21:22:10 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

Hope this helps