Multiple instances on OSX incorrectly claim to be running the OSC serv

When I run multiple instances of Renoise on OSC Yosemite they each use the same OSC server settings. The each say that the OSC server is running. However, if you send an OSC message to that port only the first instance will respond.

To reproduce:

Start two or more instances of Renoise from a terminal, using this command for each instance:

open -n /Applications/

Check the OSC configuration for each. Check that Enable Server is checked, and note the port number. There is a message showing “*** Server is up and running” . This same message appears for each instance, and each instance shows the same port number.

The expected behavior is that all but the first instance should indicate that the port is in use.

Send an OSC message to the configured port. (For example, send a /transport/start message).

The first instance responds to the message; the others do not.

If you change the OSC port of the other instances (and restart the OSC server) then they respond on that port.

This is with Renoise 3.0.1. If, while I have these multiple 3.0 instances running I also open an instance of 2.8.2 that also claims that the OSC server is running, even if it is configured to use a port already in use by another instance. If I then close a previous Renoise instance that is using that port, then the next instance configured for that port will start responding to OSC messages.

BTW, this appears to be true on Ubuntu as well. I can run multiple instances (different or same version) and all of them say the OSC server is up and running on the same port. But only the first instance started that is configured for a given port will respond to OSC message sent to that port.