I have a ubuntu system (version karmic) and whenever I reboot or remove and reinsert my usb keyboard udev creates multiple devices for the same keyboard.
lsusb only shows one keyboard "Chicony"

$ lsusb
Bus 002 Device 010: ID 04f2:0760 Chicony Electronics Co., Ltd
Bus 002 Device 002: ID 046d:c054 Logitech, Inc.