There are two people in the box, people who stand in line 1 to below the other side and another man took a header into the bottom of the other side, it seems that there are two pieces missing.
Two people in the box. The first leg slipped down the other side. And another man headfirst down the other side, making it seem that the lack of a second timber.
There are two people in a box, who 1 insert pin down of the other side. And the other head down the other side, thus making it seems lack of a 2 pieces.