I think Amsterdam is capital of lots of 'things' or 'actitivities'!
Yes, one of a handful of cities with two IATA codes & one airport - CAS/CMN & PEK/BJS spring to mind. Correction - Beijing also has NAY, but PEK refers to Capital Airport, not a generic code for the city.
Whoever designed the IATA coding system (err IATA perhaps!) without disambiguation between so many cities and their respective airports (GLA <> PIK etc) created a major oversight!
So back to PLH, what will happen to the code? The land is presumably reasonably attractive to developers, being so close to the city?