I held a NZ ATPL and current Australian ATPL. When it was obvious I was never going to get a job in NZ I didn't renew the NZ medical and didn't send in regular updates re I/F currency etc. However I kept my Australian ATPL current - instrument rating etc.
Job later came up in NZ so I applied for the Trans Tasman Agreement option and sent in the paperwork to NZ CAA.
They replied I could not have a NZ ATPL via the TTA because I already had a permanent NZ ATPL. But, as the NZ ATPL was expired beyond five years I was up for a NZ Air law, Medicals , prof check and instrument rating. Big bucks
So I said no problem - just cancel my old NZ ATPL and give me a new one based upon the Trans Tasman Agreement. No way said the NZ CAA - you cannot have two NZ ATPL's.
I don't bloody want two ATPL sez I - I just want one to get a job. Stiff cheddar they said - there is an anomaly in the system and we can't help you mate. Either come to NZ and start all over with medicals, instrument rating test and prof check to regain a NZ ATPL or forget the whole thing. By then the job had gone so I gave up the idea. Some anomaly...