Don't suppress the whole event, just add context metadata

plugin/multiplex/client.js

@@ -7,6 +7,6 @@
 		if (data.socketId !== socketId) { return; }
 		if( window.location.host === 'localhost:1947' ) return;
 
-		Reveal.navigateTo(data.indexh, data.indexv, false);
+		Reveal.navigateTo(data.indexh, data.indexv, 'remote');
 	});
 }());

plugin/multiplex/master.js

@@ -27,6 +27,6 @@
 			socketId : multiplex.id
 		};
 
-		socket.emit('slidechanged', slideData);
+		if( event.origin !== 'remote') socket.emit('slidechanged', slideData);
 	} );
 }());