I don't know ghost4linux, but I use Ghost on my Windows desktop, and the concept there is that you must have Ghost installed on every system that you want to backup. So if you have Ghost installed on multiple systems, you can of course back up multiple systems to the same external hard drive. I think it's the same for ghost4linux.
What i am trying to do is clone one harddrive to many many others but i dont want to do it one at a time. I am trying to find a program that can ghost more at once.
So what you want to do is the other way round: installing/restoring instead of backing up. SystemImager might be interesting for you: http://www.howtoforge.com/howto_linux_systemimager http://www.howtoforge.com/dedicated_server_backup_restore_systemimager