Something that was completely overwritten can't be recovered, ever.
This is by the nature of a (flash-like) digital memory, which does not have any remembrance of its previous state.
So we just need to compare how many files we expect overwritten with what we got.
Also, as the card fills up, you delete files from it, and take more shots, the shots taken last tend to fragment
- i.e. they are stored in several nonadjacent blocks, rather then contiguously.
Fragmented image files typically cannot be recovered after format
unless
Klennet Carver is used.
So, I'd say there is nothing more in there.
- Originally, there was 200 pics on card (old layer).
- You formatted it and took 160 pics more (new layer), which were written over then old ones.
- Now there are 160 "new layer" pics, and about 40 "old layer", which is all we can recover.
- Taking into account the fact that "new layer" is larger res, hence larger size, I'd expect the result worse than 40 images.