This is Rihanna's second style showdown in one week, but this time, SHE'S the copying culprit.

Just a few months after J.Lo rocked an asymmetrical leather Lanvin dress to "The Back-Up Plan" UK premiere, Rihanna was spotted wearing the same edgy number while out and about in Hollywood.

I think the dress proved the perfect fit for both diva-licious ladies, so this one's a toss-up for me.

Photos (left to right): JCalderon/Splash News; Jon Furniss/WireImage