You can export the machine keys and import them into all the servers so that decryption works. The UI for Server Beta 3 includes a feature called Shared Configuration which will allow you to do that. Click Export... and it will encrypt the machine keys, copy them along with applicationHost.config and administration.config to a path. After that, from all the other machines you can select "Import..." and it will import the machine keys and point the config to the shared configuration.