there is an emergency key that bitlocker can use, which is made when you first set it up. I haven't played that much with it, but I think you can use this key to unlock the clones.
from
BitLocker Drive Encryption - Wikipedia, the free encyclopedia:
The "Transparent operation mode" and "User authentication mode" of BitLocker use the TPM hardware to detect if there are unauthorized changes to the pre-boot environment, including the
BIOS and
MBR.
[18] If any unauthorized changes are detected, BitLocker requests a recovery
key on a USB device, or a recovery password entered by hand. Either of these cryptographic secrets are used to decrypt the Volume Master Key (VMK) and allow the
bootup process to continue.
[18]
so if you cloned the whole drive and put the clone in a new machine, it would detect that changes have been made and request the emergency key.
If you read that wikipedia article, the part about setting it up with the 1.5gb separate volume and the 'preparation tool' are included in the automatic setup of windows 7 (i think)
it is a bit scary lol