* Dylan Sprouse: He's actually released a few songs independently, including "Dismissed" and "Taking on the World," showcasing his vocals. He also sang in a few episodes of the Disney Channel show "The Suite Life of Zack & Cody."
* Cole Sprouse: He doesn't have any official releases, but he's shown singing talent on "The Suite Life of Zack & Cody" as well.
In summary, both brothers have singing experience, and Dylan Sprouse has even pursued music more formally.