I don’t think you can spawn multiple objects using one behavior.
That’s why I suggested an idea to do this. Being able to select an area of objects and being able to spawn that section using only one spawner. You currently have to have a spawner for every individual object, which is why not a lot of people dabble in decent random generation for top-down games.
Chunk Load, Spawn Multiple Objects at Once - Feature Requests - Flowlab Community
I don’t know if this will ever become a feature in the future but considering you can copy and paste sections within the map editor, you can copy and save large quantities of objects as an ID or code. So, I suggested a way to do this during the game instead of just the editor.