The loco labelled NZR is a WW1-Telefunken, built by Oberursel in Germany. This was a single cylinder petrol/mechanical, supplied to one of the German overseas radio transmitters as a construction and service locomotive. Several of the German overseas colonies with telegraph or radio stations had 2' gauge railways.
The other loco is a Malcolm Moore. These were built for the Australian Army during WWW2 and were powered by a Ford Flat head V8. These were a kit available locally in 1/43 and 1/32 scales.
It was probably one of the most successful and forgotten "invasions" of WW1. See http://navymuseum.co.nz/worldwar1/battles-operations/new-zealand-s-capture-of-german-samoa-august-1914/ During WW1 New Zealand was asked by the UK government to occupy the German wireless station in (German) Western Samaoa to deny Germany radio coverage in the Pacific. At the time Admiral Graf von Spee was running a very successful commerce raiding operation with a fleet of cruisers. This led to the NZ landing force being reinforced by the Australian Squadron of a battle cruiser and 2 modern cruisers before heading to Western Samoa.
I finally found the photo of the commandeered loco with NZR - see