Can you do multiple layers at the same time? Yes. Can the be on the same branch / trunk? Yes.
Key thing to understand how layers work.
There is a sapflow from the roots to the rest of the plant providing the plant with water, nutrients.This is through the wood of the plant.
There is a sapflow from the leaves into the plants, all the way to the roots with water sugar and hormones. These hormones signal the roots: I am actively growing, go catch up and grow too. This is through the bark.
Interrupt the bark flow and the hormones signaling: We need roots stops at the upper cut. Under the right conditions (Moisture) the tree will grow roots. As the waterflow through the wood continues the top stays alive.
If you want a second layer on the same line, you will need to have a strong growing folage mass on that section.
In your case, it looks like you only have one weak branch on the middle segment. I do not thing it will give you enough to get roots.
I would this year layer of the whole top section (Both pieces you want to keep, so layering at the lowest cut). Let it grow using as much foliage as you can get to grow a new root system. Next year you layer the top from that one, using the bulk of the foliage.This way you get to work on closing the main chop on the old plant as soon as possible. And you have the maximum amount of foliage to establish the layer. And for the next season, you have a large crop of foliage to drive the net root growth.
