The double paradiddle is a fun rudiment that is based off the single paradiddle. It is a 12 note pattern that is often used in a 12/8 feel, or in beats and fills with a triplet feel. That makes it perfect for Jazz, Latin, and other world styles.
If you've already played a single paradiddle, you'll notice just how similar it is to this double paradiddle. The only difference here is that you play four alternating single strokes instead of two. So, you simply start with four alternating singles leading into a double. Then, repeat that pattern leading with the opposite hand, and you have the entire 12-note rudiment.