Numbers & Numbers
:)
Aside from the two numbers each in the four theme answers (each is a song with a number in the title), there are three other number references and at least one other song title, not clued as such. That's four more numbers equalling twelve altogether. But you'll have to look as the unclued song title may slip detection.
12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12