Moving Category Views - Now appears in both?

We had a host which had been originally setup in the routers Category however it really should have been under the server category.

We moved it host snapshot, used the Category drop down and moved it into servers.

It then proceeded to been seen in both Routers and Servers?

We then tried the following. We deleted the instance of the host from the routers section thinking that it may have created a second instance. It deleted both... but that was not unexpected.

So added the host again but this time selected Add Server under the servers overview. It added this time as a server no ghosting of it in routers.

Ok, so why did it ghost when we moved category? How do we get around this so we don't have to completely remove a host and re-add it in future as that is time consuming and I don't want to have to re-setup checks and notifications for a host for something that should be there.

Thanks

Brad