To display different beats in multiple stores is actually quite simple, you just need to create multiple configurations and make use of playlists - so you will need a platinum account for this
Create a new playlist by going to
Dashboard -> Collections, then click the green
Click Manage Music, select the beats you want to add and save
Then create a new configuration, click
Tabsand select your newly created playlist. For information on creating configurations, please click here
Save your configuration and embed your code on your site. This store will now only show the beats on this playlist
Repeat as many times as you like!