Obviously this new network will be doomed to fail in that there is essentially no reason for people to join it, but if you can get a couple of friends to join it and become nodes then it's at least possible to create a new Bitcoin network, no? And of course the (eventually 21 million) bitcoins created in that network won't be fungible with the bitcoins in the original network.
I mean, with other types of software you can make identical copies. Can one do the same with Bitcoin?
"Doomed to fail"
"Essentially no reason for people to join"
"Won't be fungible"
Good luck with getting your friends to join with that pitch
Fortunately the reason I aksed about it was not because I wanted to create a new Bitcoin network but because I needed the answer for a thought experiment.