Clone bootable USB drives
Solution 1:
In Linux you can use just
dd if=/dev/sdb of=/dev/sdc
(assuming that sdb is source and sdc is destination usb memory)
In Windows you can check out for example this tutorial.
Solution 2:
Late to the party, but ImageUSB is also a very good option. It clones the drive exactly, including the MBR. Note that you want both drives to have about the same amount of space, as if you write a 4GB image to an 8GB drive, you'll only be able to access the first 4GB until you reformat.
http://www.osforensics.com/tools/write-usb-images.html
Solution 3:
There is an windows version of dd available, too. If you have some knowledge of the commandline it is easy to use. dd for Windows
If you don't understand the manual i could try to explain it for you. It is free, fast small and simple. It could although be placed in an BartPE image.