Two figures for the same coin, taken from two places at the same moment, can differ and both be correct. That is a structural property of these assets rather than a fault in either source, and it follows from what sets the price in the first place. Nothing stands behind a crypto-asset the way an issuer stands behind a security or a central bank behind a currency; as the Reserve Bank puts it, cryptocurrencies are simply worth what people are willing to pay for them in the market.
The same asset trades in many places at once, each with its own order book, participants and depth, and those books do not clear at identical levels. There is no exchange session that gathers every order and strikes one number, which is the mechanism that produces an official closing price for a listed share.
Australian regulation treats this as the starting condition. For exchange traded products holding crypto-assets, ASIC’s guidance says the pricing basis should be an index that reflects a substantial proportion of trading activity in the relevant pairs in a representative and unbiased manner, is designed to be resistant to manipulation, and follows recognised benchmark selection principles - and that pricing mechanisms relying on a single crypto-asset spot market are avoided. A regulator setting out how to construct a price is describing the absence of one to pick up.
An Australian-dollar figure then adds a step. These assets trade overwhelmingly against the US dollar, so a price in Australian dollars is normally a cross: the asset’s US dollar price combined with the Australian dollar’s rate against the US dollar, the same construction the Reserve Bank uses to publish most of its own currency pairs. That makes two independent moving parts, and an Australian-dollar figure can move over a period in which the asset did not move against the US dollar at all.