Diva Mariah Carey has hushed speculation that she is planning to collaborate with the pregnant Jennifer Lopez, by insisting it would "never happen".When asked about a possible duet on a US TV show, the Honey singer replied: "I'd rather be on stage with a pig! A duet with Jennifer Lopez and me just isn't going to happen."Ouch! Shall we take that as a no then, Mariah?This isn't the first time the divas have displayed public rivalry.In 2001, Jennifer, 38, popularly angered Ms. Carey, 37, when she sampled two songs from the soundtrack to Mariah's movie Glitter in two versions of her own hit track I'm Real for her album J Lo. Shortly after the scandal, Mariah was interviewed for German television and when informed that J Lo has eight hours of sleep a night, Mariah responded: "If I had the luxury of not actually having to sing my songs, I'd do that too."