If I were guessing, the structure of the package is designed to fit different music formats. So, if you're coming off a break into a rock song, you can play the rocky jingle. If you're coming out of the break with a song that has a slow start, you've got the love/acoustic guitar jingle. It's so you can match the right jingle to the right genre. Makes for some great segues.
Oh, and you'll be pleased to know that I'm hearing standalone jingles being used between songs too.