Ahhhh, the hills are alive with the sound of catfights now that reality TV cast mates, sisters-in-law and reputed enemies Heidi Montag and Stephanie Pratt each have booked themselves into Vegas for parties this weekend.

Oh — as the kids say — snap!

"I haven't talked to Heidi or Spencer since September," Stephanie told Fancast.com on April 6, speaking of her equally camera-shy brother Spencer and his wife, Heidi Montag. The same day, UsWeekly.com quotes Pratt as saying that Heidi and Spencer "don't want me in their life."

Pratt will turn 24 at midnight during her Saturday, April 10, birthday party at Lavo Nightclub and will follow it up with a do-over Sunday at Tao Beach. Montag will host her own party at Liquid Pool Lounge on Saturday afternoon. Coincidence?

Lucky break that the parties aren't concurrent. Still, let's pray the two don't run into one another in line for the Deuce or there could be untold consequences for Montag and her 10 recent cosmetic procedures.

Of course, once they're in town anything could happen — they could (gulp!) make-up? — but by our count, going into the weekend it's Stephanie 2, Heidi 1. Montag may have first, dibs but Pratt gets the last licks.