This is because you’re not queuing the audio, you’re basically telling it to play two tracks at the same time.
Easiest fix would probably be to add a wait command with the length of the first audio file. Insert that in between audio file and your message.
Oh that’s because I messed up . cast-web-api v1.0.2 is v1.0.0, I had to increase the version number for npm to publish it.