Yes! You can add multiple soundtracks to your video to play at the same time.
To add multiple music tracks:
Click on the music file or voice-over to add it to your animo.
Click on another music track or voiceover and add it to the sound track as well.
You can add as many soundtracks as necessary.
To adjust the volume of the soundtracks, click on the soundtrack on the timeline and from there you can adjust the volume of the track.