I wouldn't trust ceramic laid on ceramic because I don't know how you could get a decent bond.
Maybe on top of a non-glazed tile but I still wouldn't try it. You might be able to put a thin concrete backerboard (1/4") over the existing tile but it will be a real chore securing the backerboard solidly to the material under the old tile. If you can mark the existing joints and put the screws down thru the old grout joints --maybe.
If I found an adhesive that claimed it could bond a tile to a glazed tile, I would try it first and see if it creates an acceptable bond.
But if the old tiles are cracked, uneven or otherwise damaged, it will cause problems.
Maybe on top of a non-glazed tile but I still wouldn't try it. You might be able to put a thin concrete backerboard (1/4") over the existing tile but it will be a real chore securing the backerboard solidly to the material under the old tile. If you can mark the existing joints and put the screws down thru the old grout joints --maybe.
If I found an adhesive that claimed it could bond a tile to a glazed tile, I would try it first and see if it creates an acceptable bond.
But if the old tiles are cracked, uneven or otherwise damaged, it will cause problems.