This adobe article states that:
When you run Flash content in a web browser, Flash Player typically runs in a separate operating system process. There's only one process for all the SWFs running in that browser, including any related worker threads, and Flash Player manages the execution of these SWFs so that it looks like they're running independently. Each running SWF is known as a player instance, and this corresponds to a session in Scout. Worker threads are player instances too. For AIR content, there's only one main player instance, plus any workers it uses
So separate scout sessions are started for Worker SWFs (separate runtime instance). If you simply use a Loader, those telemetry data are included in your main session.