Enter Elaine Carroll. This girl is a fucking genius. Not only does she know how to dress like Mary Kate, but she's got that weird lip-smirk-smile-grimace thing down COLD. And when she plays Ashley as well? It's like watching the original Parent Trap from the 60s. Here are a couple of my favorites:
I was surprised as anyone when Mary Kate decided she was going to become a "legitimate actress". But to my surprise, she was actually pretty good on Weeds (it also helped that season 3 was the last decent season of that show).
The other thing I realized was that I literally hadn't heard either of the twins speak since their days on Full House. For good measure, here's one more...since Bodyguard is kinda hot: