PAL and Airphil Express Codeshare Flights

I just learned about this agreement when I booked my friend and her family's flight to Boracay recently. They were surprised to board the Airphil Express fleet when they have Philippine Airlines flight tickets.

So what is a codeshare flight? Code sharing or codeshare is an agreement between two carriers where a flight operated by an airline is jointly marketed as a flight for one or more other airlines. 

The term “code” refers to the two-character airline designator code and flight number in flight schedule.

The airline that operates the flight (the one that provides ground handling services, the plane and the crew) is called the operating carrier thus, codeshare flights has this information: “Operated by AirPhil Express”



Philippine Airlines (PR) has codeshare agreement on these routes:

Domestic - with AirPhil Express (2P)
Between Manila and Busuanga
Calbayog
Catarman
Caticlan*
Masbate
Naga
San Jose
Surigao
Tuguegarao

Between Busuanga and
Puerto Princesa
Between Cagayan and
Davao

Between Cebu and
Bacolod
Cagayan de Oro
Caticlan *
Iloilo
Ozamiz
Tacloban
Zamboanga
Between Zamboanga
Cagayan de Oro
Davao
Jolo
Tawi Tawi

*Flights may be rerouted to Kalibo due to runway restrictions.InternationalBetween Manila 
Abu Dhabi – with Etihad Airways (EY)
Bahrain – with GulfAir (GF)
Doha – with Qatar Airways (QR)
Dubai – with Emirates (EK)
Kuala Lumpur – with Malaysia Airlines (MH)

Between Cebu
Hongkong – with Cathay Pacific (CX)

So okay, we learned about that. But can it also mean that Pal's airfare should also be the same as Airphil Express'? Cos today I tried to book a client to Puerto Princesa, and Pal's airfare amounted to a whopping Php 10,000++ roundtrip. It's a code share flight and operated by Airphil Express. That same flight, same date, same time is just Php 2,900 when booked via Airphil.