The two implementations are still kind of competing for the name bitcoin, hence they could use the same daemon name and same folders.
Remember this during installation as well and make sure you are creating executables with different names.
When you launch any of the two daemons, by default, it will try to load the configuration from
~/.bitcoin/bitcoin.conf, which means that for one daemon you will have to create a specific directory with a dedicated config file.
bitcoind --config ~/.bitcoin/bitcoin.conf
bchd --config ~/.bch/bch.conf
The ports and the directory are just for explanatory purposes, the only important thing is that they have to differ between the two configuration files