title: How to play two (or more) audio files simultaneously with just_audio and audio_service?
body: <p>I tried reading through the project readme and issues on Github to see if it was a possibility to play two or more audio files simultaneously using the <code>just_audio</code> and <code>audio_service</code> plugins for Flutter. Has anyone achieved something similar using these plugins or similar ones? I currently use these plugins in production so it'd be preferable to stick with them to add the desired functionality to the app.</p>
  <p>Any help would be greatly appreciated, thanks!</p>