Is it possible to unlock it with the metal key inside the extra fob I have? It won't recognize the fob.

This is for a 2011 Cayenne Turbo.

 

yes you can. you need to pry off the plastic cover on the door handle to access the lock. from p. 33 in the owners manual:

The vehicle cannot be unlocked
Unlock the driver’s door with the emergency key in the door lock: 1. Insert the emergency key into the slot under
the door handle and remove the cover of the
lock. 2. Unlock and open the driver’s door with the
emergency key. 3. Switch on the ignition within 10 seconds to
prevent the alarm system from triggering.

or you can always call 1 800 porsche :-)