If you want to create a lot of them from script you can do:
var MyNode = preload("path/to/the/node.tscn")
and:
var new_node = MyNode.instance()
#if you want to change something in the node (for example the position here):
new_node.position = new_position
scene.add_child(new_node)
to instance one. Then just use a for loop to create hundreds of them.