You should try to use a different data directory for your second node, if you are running it on the same machine.
Otherwise it uses by default the same data-dir as the first node, but the filder called "newchain" does already exists here.
This is done with the parameter --datadir, that you should use on every multichain-command of the second node.
That was the problem I had.
Maybe that already helps? Also check that you use different rpc and p2p ports since otherwise I think they are going to use the same ports.