One week after Ashlee Simpson's infamous appearance on "Saturday Night Live," Eminem is now being accused of lip-syncing to his song "Mosh" on the show.

Twice Eminem had his microphone at his side while his vocals continued.

His publicist, Dennis Dennehy, told the New York Daily News Tuesday that Eminem was "rapping live" to "a backing track of his own vocals."

"It's hip-hop," Dennehy told the paper. "Artists sample their own voices all the time."

Meanwhile, Jessica Simpson responded to reported comparisons between her sister, Ashlee Simpson, and Milli Vanilli -- the vocal duo that was stripped of a Best Artist Grammy when it was discovered they were lip-syncing.

"Ashlee is an amazingly talented person and the fact that people are calling her 'Milli Vanilli' is absolutely obscene and ridiculous," Jessica Simpson told "Access Hollywood." "She's already sold three million records which is more than I sold in two years. She's proved herself."