The break up jerk is essentially a two-stage with the again foot landing first and so getting traction first. This has the influence of pushing the bar forward underneath the bar as it locks out overhead.
This training teaches the correct “prancing” motion of the front foot while reinforcing the drive from the shoulders in front of the neck. If this is a problem of yours or just one of your athletes, contain the motion early in the session right until the footwork turns into perfectly ingrained. As far more proficiency is attained, the training can be gradually moved even further again in the work out right until it can be eradicated completely.