How Jeremy Irons used Alexander Technique to portray twins

A recent listicle at MoviePilot titled "Double Trouble: Here's What Happens When Our Favorite Actors Come Face To Face With Themselves" states:

Initially, Irons had two separate dressing rooms for each character, both with their own wardrobe, but he soon realized that “the whole point of the story is you should sometimes be confused as to which is which.” From that point onwards, he used a single dressing room and mixed the wardrobes together, finding an “internal way” to play each character differently. Irons cites the Alexander technique as the reason he was able to give the characters “different energy points”, weighting one brother on the balls of his feet and the other on his heels. He developed different postures and voice modulations for each as well.