The requirement in the ATO manual is to pass the minimum of either the NDB or VOR during the test.
"A “pass” assessment in the flight test for the rating depends on satisfactory performance in:
1) General instrument flight
2) Use of NDB or VOR as a navigation and approach aid.
An unsatisfactory final performance in any item or procedure in these areas results in an overall fail assessment for the flight test. An unsatisfactory performance in the use of radio navigation aids other than the NDB or VOR does not result in a fail assessment."
The Instrument Rating Application (Form 645) item 34 for the NDB requires the ident to be monitored during approach. Item 57 requires the correct identification of navigation aids used.