I Guess so. If you are relying on you Navigation Database (NDB) to perform the approach in Overlay and you have the same remark to an RNP ACH, what would change?

I don't see that. The MEL item 22-81-03-01 and associated Operations Procedures A/B refer to the RNP APCH, which has per se nothing to do with a VOR or NDB approach. Dual GNSS sensors, dual FMS, dual air data systems, dual autopilots etc are generally not a requirement for either. Refer to ICAO Doc 9613 - 6.3.3.4.3.

Thank you for your comment to my issue. Your answer is absoulately correct. But my thought, when VOR or NDB approach is flown with GNSS Overlays on Non-precision Approaches in Navigation Data Base, as fully managed, vertical navigarion is Baro VNAV which is based on current barometric altitude and requires two altimeter setting source like FCU channel.
Best regards

That is exactly the point. From my point of view the question is related to the used of the FCU automation to fly this or that approach. If the MMEL is limiting to fly an Navigation Database-based approach, should this procedure be extended to any approach procedure using and NDB (Navigation DataBase)?

Maybe the question if, the Failure/Deferred Item related in the MMEL that limits the RNP APCH procedure is protecting or avoiding what?

The MMEL item that limits the RNP APCHs limits these because the redundancy required for the approach is no longer provided.This redundancy is not required for other approaches, such as a Non-Directional Beacon (NDB) approach, even if you use the FINAL APP mode until the MAP. If you feel other approaches should also be limited, you can always bring that forward with your operator. Your operator can then add more restrictive limits to his MEL for that item.

Dear all: Does anyone know why two FCU channels are required for an RNP APCH?
It may answer H.C.Pekel's question about the requirement for a fully-managed NPA.

Interesting point Robert Gottwald. Just to "finish" the understanding, 1) why the redundancy is not required for other approaches, please? 2) Where we can have this information, on which approach a redundancy is needed or not?

Sorry, just realized I never responded to this. Two FCU channels are required to not have a single point of failure. This is always a requirement for RNP AR APCHs already by the navigation specification. For RNP APCHs AP/FD is not even required when the TSE is otherwise low enough.
If the MMEL explicitly states "RNP APCH operations are not permitted. For aircraft with the RNP AR capability, RNP AR operations are not permitted", then this applies to both RNP and RNP AR APCHs.
Which redundancy/equipment is needed depends on any applicable (your operator's) MEL restrictions and operating minima (both general and aerodrome/approach-specific).
Also refer to your FCTM "APPROACH USING FINAL APP GUIDANCE" or similar section.