I had another look at this picture and came to the conclusion that we don't see Amalie and Clotilde in this picture.
1.) The sisters resembled their mother Clémentine d'Orléans, who had very chiselled features (just think of her nose!!), a lot. But in this picture, I cannot see any resemblance to Clémentine.
2.) Clotilde was more than two years older than Amalie. So she had to be a bit taller than her younger sister. The girls on the pic almost have the same height.