It looks like RJ Mitte appearing on shows in which the main character is secretly leading a double life that no one knows about is actually somewhat of a trend—because that there is Breaking Bad's Walt Jr. himself, chilling in the background of a 2007 episode of Hannah Montana.
According to IMDb, it was his first acting credit—he portrayed the unnamed "School Jock"—and what a glorious acting credit it was.
Alternate universe headcanon where Walt Jr. grew up in LA and attended high school with Miley Cyrus who, for some reason, NO ONE realized was also a pop star named Hannah Montana. Maybe Walt Jr. finds out because he's not an idiot! And after he does, he can't even enjoy his pancake breakfast in the school cafeteria because
...or something. Just an idea.