When the blockchain underlying a cryptocurrency is forked, both the ownership status of all the currency is cloned, and everyone possesses the coins they had on the original blockchain then on both forks.
That is usually not a problem, because the value of these coins is usually "split" and quickly one of those currencies will be worth hardly anything.
But what happens with NFTs and other smart contracts on a blockchain fork? Some NFTs give you rights to some off-chain things, like e.g. they represent ownership of something.
If the chain is forked, one copy of the NFT might be sold, while the other one isn't. So the same NFT can now have multiple owners on different chains.
Has this happened before?
How is this usually handled?
What does that mean for someone owning/buying NFTs with off-chain implications?