This is a complicated concept for me, but I’ll do the best I can to articulate it. I learned about this in acting class:
You must memorize your lines in order to forget them. In the scene, the words don’t matter. Just react honestly.
Acting is not just reacting. It’s listening and deciding your actions based on the energy you receive from your scene partner(s). Here’s one of the many instances where theater and dancing overlap. Can this not apply to our dancing, too? I suffer from “headiness” when it comes to the arts. I think too much.
Moving on, this does not imply under preparation. On the contrary, practice so well that you don’t have to “retrieve” your lines or steps. Once that’s done, trust yourself to remember. So, where does this “double reality” come in? I’ll paraphrase a story he was telling our class: “It’s one of my pet peeves when an actor smashes a prop piece and someone remarks ‘Yeah, but he was just so into it!’ Horse dukey. There’s no way you can truly act if you lose sight of what you’re really doing.”
That’s the ticket. If I get “so into it” that I screw up my steps, there’s no point in dancing. As a dancer or actor, you are two people. The first is yourself, the person you’ve loved and hated, the person you hide, the person that only comes out when you’re among loved ones. The second is your role, your character. Do the necessary preparation for the second, but react as the first. Yeah, it’s hard, really hard. Infusing something compelling into your craft takes vulnerability. It’s what my director means when he says “for realsies”. I cannot help but wonder how much my dancing would improve if I did with two realities.