I have tried running 2 x Instances, but i get the message the port is in use, which makes sense.
Also, the reason you get port in use error is that there are two instances on the same port (which you figured out). Just a reminder if you fix that...
By default it using port 3333 but the value of "-mport" is "-3333". The negative makes it read only. Don't remove the negative unless you put a password on it.