If you are having your alerts echoing it means it is repeating itself in the background either on your computer or in the streaming software.
First, make sure you do not have any additional pop out windows open.
Right click your URL Source and uncheck "Keep source in memory". Make sure to do this for every url source in all scenes.
Right click your Browser Source and click "properties". Check the box that says "Shutdown when not active". Make sure to do this for every browser source in all scenes.
If this does not work try removing the source completely and remake it.