Addresses are not a big deal for blockchains – they usually only take care of the keys involved (or on Bitcoin and Bitcoin-based networks, the lockout script, which locks an output so that it can only be issued by a specific user). [set of] key[s]).
Since the key generation process is based on entropy rather than on the network you are building the key for, it is highly unlikely that two people could create an identical key.
It is unlikely that any wallet I know will check the target chain for key reuse. It's just something that's unlikely to occur, provided you have a sufficient source of entropy.
Note that even if you generate (or manually copy) a key across networks, the actual "address" may still be different because Bitcoin uses base58 / bech32 addresses while BCH uses base58 / cashaddr addresses. However, this is just a coding and does not change the underlying key needed to output the output.