I know someone already answered this. But just so you know it is due to the format of the configuration files changing (they are even different sizes). It is also a problem when trying to download configurations from the web (will actually lock the xbox up in some cases). Anyways if you upload configurations I suggest putting the winuaex version number in the description.
I cant play some games (like Alien breed ) in two players mode, because i don't know how to change the mapping of buttons on the second Xbox joypad .
if i go to Controller configuration - controller 1 - change joypad mappings - change game mappings , i can change with the relative commands from Xbox joypad no 1 , if i try to do the same procedure with controller 2 , the emulator don't allow me to press the relative buttons from Xboxs joypad 2 ...
How can i configure joypad 2 to play two-players games

I hope you can help me ... Bye !
Press the correct buttons on controller 1. Don't worry, they will be mapped to the proper controller. (IMG: