Try opening System > Preferences > Sound to get the Sound Preferences dialog box. There check the option for "Music and Movies". If it is "PulseAudio Sound server" is the one that is currently selected, try ESD or ALSA. That should make multiple players be able to play audio at the same time.
Try opening System > Preferences > Sound to get the Sound Preferences dialog box. There check the option for "Music and Movies". If it is "PulseAudio Sound server" is the one that is currently selected, try ESD or ALSA. That should make multiple players be able to play audio at the same time.