I don't think that's a bug, when you pick promotions the info is only about what that specific unit will gain from it, but in the promotion tree it will show the accumulated effect of the promotions under it as well.
Operations I gives +5 control points
Operations II gives +1 command range
The promos in the pedia promo tree are not relative to a specific unit so it will show the accumulated effect of Operations I + II when hovering over Operations II.
Operations I gives +5 control points
Operations II gives +1 command range
The promos in the pedia promo tree are not relative to a specific unit so it will show the accumulated effect of Operations I + II when hovering over Operations II.