On Double Heavy
Practice taiji and doing taiji push hands is the exchange of position, time, and space. In taijiquan, this exchange is called "turning of the joint". Time and space have five layers (dimensions). Chen style calls this spiral movement, or Peng Energy.
It is therefore East, West, North, South, and Center. In the human body, it is left hand, right hand, head, feet and huiyin. There are two feet but they only represent one direction: the lower/bottom position. They are split from the point of Dantian into two. Because they are one of the same, it is not a matter of which foot the weight should be on when we talk about double weight or double heavy.
Double heavy is a problem in the synchronization of the head, hands and foot. It takes at least ten years of practice to have a basic grasp of what this means.
The original of this was in a note form hand written by Chen Zhonghua.
Source: https://practicalmethod.com/?p=2974