I am at 34 weeks and mine turned from her on side at bottom and hip breech, to now, her breech and on left and him head down and on right. You never know what they are doing in there!!
From what I have understood, if they are on top of each other they will stay that way. Mine were always side by side and was able to deliver vaginally. I'm not 100% sure if they can get to a head down position if they are on top of each other.
in both of my twin pregs baby be was "headlong breach" but the second time he turned to full breeach.
baby A went head down around 30some weewks first time
baby a went head down super early next time
deliverd vaginally with fabulous and patient docs