Ah no, it wont let me "IP Address <snip> already exists". I've already got my host called mail set to that ip (I saw somewhere some time ago that mail servers are supposed to be A records, not CNAMES, so I had to make it my main host name not an alias), with all the other services set as alias's (ie www, webmail, and so on).
Once you've got one host name set to an IP it will not allow you to give another hostname the same IP. Although on the old server, not running ebox, I had 5 hostnames as A records to the same ip in bind, it didn't seem to mind, it just meant when you ping'd the ip it resolved to a random hostname out of the list of ones assigned to it.
Andrew