Quistorff allegedly forged another certificate for Alfadhi for a 10-day sick period in October last year.
Court documents show he had signed certificates as David Montgomery.
A doctor of that name does not appear to exist in the Auckland area.
Quistorff, originally from California, had been living in Auckland for eight years and had qualified as a doctor at the University of Auckland.
He worked as a locum at an Auckland city men's clinic and had run a botox business called Guardian Medical.
Auckland District Health Board spokesman Mark Fenwick confirmed Quistorff had been a locum at Auckland City hospital until December last year.
He had been granted his general practising certificate in January 2010 and Medical Council spokesman George Symmes said Quistorff could face council disciplinary procedures if convicted.
He remains on bail and will appear again in June for a plea inquiry hearing.
