If a matter is remitted to the AAT by the Court is it ok for the same tribunal to deal with the case on remittal?

This is hot off the press...http://www.judgments.fedcourt.gov.au/judgments/Judgments/fca/single/1997/1997fca0809

As a general rule where an applicant is successful at the FCC or Federal Court and the matter is remitted back to the AAT for reconsideration then the same member should not hear the matter again.

This is a perfectly reasonable conclusion and you should insist on  in every case.