I have a Master/media server and a media server. All my servers that backup to tape run against my Media server and all my disk stage and NDMP run against my Master/Media server.
I have a policy with 2 servers in it, the first server backs up to tape without issue. The second server will only backup to disk stage, otherwise it receives the error listed above.
I have another policy that has several servers and the entire policy will only backup to Disk stage and never to tape.
In short the answer to Aaron's question is NO the tape and disk stage media server are different. However, I built them both with W2K3 SP3 from our standard server build, they are practically identical.