There’s no sign of “double trouble” from this adorable pair... they’re inseparable, and they even have their own private language.

As three-year-old Vivienne Jolie-Pitt stepped into the luxury Beverly Hills children’s boutique, she grabbed the hand of her leather jacket-clad twin brother, Knox, and squeezed it tight with excitement. Her eyes widened as a pastel-pink silk taffeta tutu came into view. Turning to her famous mum, she exclaimed, “Look, Mommy, a princess dress!”

If the Academy gave out Oscars for the Most Adorable Performance by a Toddler, it’s safe to say Viv would need to have a speech ready. The previous night, mum Angelina Jolie and dad Brad Pitt had been star attractions on the red carpet, but Viv and Knox remain blissfully unaware of the excitement of the awards night. Ange explained in one interview that she had told her tribe of children she and their dad were simply “going to work” and the little ones had replied, “Hurry home!”

Oblivious to their parents’ superstardom, the twins were last week much more excited over a day out with their mum and their grandmother, Jane Pitt. It was a chance for them to be spoiled while their four older siblings – Maddox, 10, Pax, 8, Zahara, 7, and Shiloh, 5 – stayed at home with Brad. It was most definitely, as they call it, “twin time”.

Once inside Auntie Barbara’s Kids, the exclusive LA children’s store, the two youngest members of the multicultural Jolie-Pitt clan were excitedly babbling away to one another about the luxury wares on display. While it was easy for Ange and Jane to understand Vivienne’s excitement about the princess dress, or Knox’s instant devotion to a dinosaur T-shirt – “This one’s got Rex on it,” he shouted – much of their discussion was completely unintelligible because it was in the secret “twin language” the pair have devised.

Read more about the twins’ cute quirks and very individual personalities including which one has a temper and who likes playing with mummy’s lip glosses, in this week’s Woman’s Day on sale Monday March 5, 2012.