Moving Heads PubSub creates competing instances of the same topic

[r3dcrosse]

Steps to reproduce:

1. run ./gradlew runPinkyJvm and ./gradlew runBrainJvm
2. Open browser at localhost:8004
3. Open either another browser tab or incognito window and go to localhost:8004
4. Start adjusting the eye positions on both browser windows

When two users subscribe to the moving heads PubSub and start sending updates, the server keeps both instances alive and bounces back and forth between both values in an infinite loop. This stops when one user disconnects.

It seems like it is because the UI sends an update for the moving head position, but never listens for what the position should be from the server, which is why I think we get competing moving head positions when multiple users subscribe to that topic?