By the time you pick up your second hoop, you likely already have the muscle memory down in your dominant hand, and your natural current. Your non-dominant side probably feels pretty foreign, so you will want to practice spinning on that side.
Caterina Suttin shares some effective exercises to help speed up the process of training your muscle memory on both sides in this tutorial "Drills for Twins Practice", filmed at Sacred Circularities in Bali.
Now you're feeling a bit more comfortable with your 'left' side, it's time to exercise our brain to establish a connection with both sides. The key to this, is where you bring your focus. You already *know* how to draw flowers with your right side, and keep the hoop on a clean vertical plane, but you feel your left side is still sloppy. Maybe you keep going, naturally, keeping that clean plane on the dominant side, while the other hoop is spinning more and more out of control, until finally, it flies out of your hands, or manages to swing up and hit you in the face. "WHYYYYY?!" Now, we have to evaluate what went wrong, and how do we get our 'left' side to stop being so lazy, and straighten out that plane? We shift our focus from the right side, to do this, we area really tuning in to where our mind, and body are paying attention to, and work on thinking and feeling, focusing on the hoop in our left hand. So although you are spinning two hoops at once, you are really only concentrating on the parts of yourself that feel awkward. Eventually with practice, you will be able to relax your focus, and find balance within your body and mind while introducing your twin hoop.
Practicing what it feels like to exercise your mind, and shift your attention from one side of your body to the other is a skill that will not only help you with doubles, but with introducing multiple hoops as well. This especially includes (but is not limited to) the quad hoop move; two hoops on each arm, as well as two hoops one hand.
What we are working towards is achieving a flow state, and smooth transitions, and with adding a second hoop it may seem challenging at first. (Remember when you started with a single hoop?) Your mind is a very important tool on this hoop journey. We connect with our minds when we are able to bring focus to our practice, and at the same time can help our minds find peace when we work past the challenges and grow with them. Never give up!