Popsugar Entertainment Halloween Mary-Kate and Ashley Olsen Halloween Costumes 14 Mary-Kate and Ashley Costume Ideas That Are Double the Trouble For Halloween October 28, 2017 by Kelsie Gibson View On One Page Photo 9 of 15 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 9 Kelly and Lynn, Double, Double Toil and Trouble What to wear: A blue dress, red and white stockings, a black cape, and matching witches' hats. How to act: Try to stay out of trouble, especially when it comes to the supernatural. Previous Next Start Slideshow HalloweenAshley OlsenMary-Kate OlsenNostalgiaHalloween CostumesPop Culture Halloween CostumesMoviesHalloween Costumes For Women