Australia's been accused of stealing a lot of things from New Zealand and passing them off as their own - from pavlova to Phar Lap.
Now the Acting Prime Minister says our closest neighbour also pinched our flag.
Winston Peters told TVNZ on Monday that Australia should get a new flag to "honour the fact that we got there first with this design". Australian Prime Minister Malcolm Turnbull's office has been approached for comment.
But were we really the first?
The first New Zealand flag was created in order to comply with 19th Century British navigation laws. Being a colony at the time, we had no need for our own flag until our trading ships began being impounded in Sydney.
The Flag of the United Tribes was adopted in 1834, after a group of Māori chiefs voted on three proposed designs. They rejected two proposals which featured the Union Jack, opting for a modified St George's Cross instead.
Unfortunately for them, the signing of the Treaty of Waitangi in 1840 meant all United Tribes flags would be replaced - forcefully, in many cases - with the Union Jack.
The current flag, which is one of many 'Blue Ensign' flags featuring the Union Jack on a blue background, was designed by Lieutenant Albert Hastings Markham in 1869.
It was used only on government ships at first, but was informally adopted as our de facto national flag. It was made the official flag of New Zealand in March 1902, under the Ensign and Code Signals Bill.
Malcolm Mulholland, a historian at Te Whare Wananga o Awanuiarangi and member of the Flag Consideration Panel, says Mr Peters' claim that Australia then stole that design is a common misconception - but it's not true.
"If anything it can be argued that the idea of the Southern Cross on a flag came from Australia," he told Newshub.
"There were at least six flags that employed a Southern Cross in Australia prior to the current NZ flag being designed and accepted."
Furthermore, he says flag designer Lieutenant Markham was primarily based in Sydney as part of the Australian Station.
He brought the Edith, the first ship bought by the NZ Marine Department, to Wellington - and the man in charge of the Edith was Australian George Austin Woods, who was the first man to fly the current New Zealand flag on the Wellington waterfront in 1869.
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Across the ditch, Australia became independent on January 1, 1901, and held a design competition for a new flag soon afterwards.
That sounds like it settles the argument - Australia got there first. But there are two complications:
1. It took more than 50 years for the country to officially recognise their flag.
2. The flag was designed by a New Zealander.
William Stevens, a merchant ship's officer, was one of five winners of the 1901 competition. They reportedly all submitted basically identical designs, with a Union Jack in the top left corner, a six-pointed star - representing the six federated states of Australia - underneath, and some iteration of the Southern Cross on the right-hand side.
The Otago native was declared the winner, receiving £40 for his efforts.
His flag received mixed responses from Australian media at the time. While The Age and The Argus newspapers praised Mr Stevens' design, The Bulletin - the country's longest running magazine until it folded in 2008 - slammed it as a stale rehash of the British flag, "with no artistic virtue [and] no national significance". Ouch.
Regardless, the flag was approved by King Edward VII, and gradually worked itself into regular usage over the next 50 years - formally establishing itself as Australia's national flag in 1954.
So is Mr Stevens to blame for our indistinguishable flags? Not really, as he and the other four designers with the same idea were only following flag protocol.
The Blue Ensign has been used as the official flags of organisations and territories associated with the UK since its creation in the 17th century. Different designs are 'defaced' with different emblems, such as the New Zealand flag's Southern Cross, or a crest of some kind.
The same flag design is currently used by the Cook Islands, Fiji and Tuvalu - although against a light blue background, which looks a lot nicer in my opinion - and approximately eight trillion yacht clubs across the world.
All six federated states of Australia use the Blue Ensign for their respective flags as well.
So neither country really 'stole' the other's flag. Rather, we both abided by what was common practice in the Commonwealth at the time: adapting the same boring design.
If Australia was to change their flag, they might consider switching to their Red Ensign, which is the official merchant shipping flag. It's the same design against a fetching red background, which would distinguish it from ours while still looking distinctively Australian.
But we're unlikely to see a flag change from either country in the foreseeable future.
If there's one thing we learned from John Key's doomed flag referendum, it's that even the best graphic design in the world (#RedPeakForever) can't beat good old Antipodean apathy.