You mean plastic surgery to alter the shape of a kidnapped childs ear shape? I guess it could be possible. I'm not sure how likely as the kidnapper would have to take a child to a surgeon to have that done. It would be much easier to change a childs hair color or other distinctions which the kidnapper could change themselves without needing a medical professional.
In addition to the ears, I think Adji's eyes are much larger than this available for adoption childs too... the dates are off of the pictures as well, IIRC. The available for adoption picture is dated prior to Adji being missing.
ETA: Also, depending on the circumstances which led to this child being available for adoption, parental abandonment, or parental rights terminated, loss of parents. There is likely a paper trail which could be ordered by LE to determine how this child came about being available for adoption. LE could rule out that way if the paper trail is not in order.
While they look alike, too many things point to this child being ruled out as Adji.
jmo