Two drobo NAS on one network causes premature 'Server has closed down' events.

Question

We have a Drobo setup with a fixed IP on ethernet which we've named BoxA. It shows up in the finder list, everyone can connect to it and share files.

We brought a second Drobo to backup the first, this was given a different fixed ip and a different name BoxB.

When we connect BoxB to the network all the clients which are connected to BoxA receive the message "BoxA has closed down" clicking on BoxA on the finder reveals the content of BoxB.

Any idea what might be causing Finder to display this message? Why would it see two different network servers as the same?