Oh yes, it's been heavily altered, possibly shortening the bodice, I think all those tucks weren't there originally, maybe it didn't have the shelf bust and this has been created by taking the making the dress smaller in size.
They probably couldn't recreate the chiffon overlay on the top half nicely over the altered shape so did away with it.
If you compare the thread used to sew the size tag in to all other stitching you will be able to see what is original and what is not.