However, this raises an interesting question: in the event of a private key collision, where two different users independently generate the same private key and sign messages with it in the same block, wouldn’t that create a conflict? It seems like a situation analogous to a "double spend" or a "double reserve" of the same key. Both parties could claim ownership at the same time in the same block.
If you use a reliable and secure script to generate the private keys (any of the reputable wallets will do) then you haven’t to worry about private key collision. The chances that such script will generate the same private key more than oce are astronomically small.In your case, the odds are even lower since the identical private keys need to be generated in a short period of time so that the signed messages get included in the same block.