It seems that the buoyant feeling natural talalay provides is partially due to stretching from the non-compressed parts of the layer to the parts being compressed.
For that reason, I would imagine the two 2inch layers might feel more plush, less supportive, and less buoyant compared to the single 4 inch slab
Maybe slightly but I don’t know anyone who sells 4" layers of Talalay.
Yes, two 2" topper would likely be a bit plusher than one 4" topper unless you have the two 2" layers in a fairly tight topper cover. For us (Sleep EZ and Latex Mattress Factory) you could order two 2" layers but just mention in the comments section at checkout that you want us to seam the two layers together. Just FYI, we use a non-toxic water-based glue that is Green Guard certified against harmful chemicals and off-gassing.