Milk and cereal is a homogenous thing. Lasagna is not.
You can sprinkle in some more cereal and milk and it's a bigger serving. You can take a club sandwich, bread, stuff, bread, stuff, bread, and add another layer of stuff and bread and you've got a growing club sandwich. You can remove stuff-bread layers and it's a shrinking club sandwich.
You can't take two complete burgers distinct bottom bun, stuff, distinct top bun, put one on top of the other, and call it one big burger. Cooked lasagna has a bottom, has a top, and those bring different textures. At best you could take lasagna 2, remove the top and bottom layers, split lasagna 1 in the middle and shove lasagna 2's defiled remains in there and if appropriately inserted and layered get away with saying it's 1 lasagna but what even are we doing at that point.
I'm with
Tobor .