New Zealand has two national anthems of equal standing, which according to the Government, makes it unique. The first is "God Save The Queen" (no, not by The Sex Pistols
); the second is "God Defend New Zealand," which may also be unique, unless there is somewhere another national anthem that was composed by two non-indigenous authors who were born in different hemispheres.
"God Defend New Zealand" started life as a poem in 1870. Thomas Bracken (1843-98) was actually born in Ireland but immigrated to Australia as a child before moving to Dunedin, New Zealand as a young man.
In 1876, a competition was held by a newspaper to set it to music. The 10 guinea prize was won by John Joseph Woods (1849-1934). Woods hailed from Lawrence, New Zealand but was born in Van Diemen's Land, what is now Tasmania. Like Bracken, he was of Irish stock, and was said to have composed the music in a single sitting.
The new, complete five verse song was first performed at the Queen's Theatre, Princes Street, Dunedin, on Christmas Day, 1876. In 1940, the Government purchased the copyright, and it became the country's national hymn, becoming joint national anthem in 1977.