I see this a lot in Intermediates / Intermediates +.
In my opinion its a way to get the inside hip inside the skis more quickly,
and I tend to see it more in skiers that learned on straight skis.
It typically is followed by "dumping the hip" inside the turn.
I'm not a fan of this - skies are now on different arcs and the Center of Mass is now 'between the feet'
one foot is ahead of the hips the other is lagging. And it will have to be reversed at the next transition
So I would focus on the inside knee/ankle release of the old turn:
Fan exercises with uphill turns initiated with the inside (and uphill) knee to experience inside ski pulling outside with it.
Garland releases with down the hill turns initiated with the downhill knee.
One footed skiing from finish to neutral to initiation (big toe edge to flat to little to edge) might help if they are ready for that.
While you didn't mention it, correct pole direction and timing may help "pull" the skier
across the skis (both skis release simultaneously)