Did you power on the source machines since you took the clones? What has probably happened is that the machine authenticaion ticket has updated with AD and the source machines, but the clones won't have this. To log in on the clones again, remove them from the domain and re-add them. This will then mean that the source servers won't be able to authenicate against the domain though.
If you are needing to keep and use both source and clones I would SYSPREP the clone and give it a new name and IP.