### Godot version

v4.0.beta15.official [4fa6edc88]

### System information

Windows 11

### Issue description

When drawing a polygon in the editor, several duplicate vertices are added to the polygon array for each click.  In the image below, I clicked three times to draw the triangle, but got 10 entries.  The number you get varies, though I don't know why; I've seen hundreds of points from drawing a hexagon.  I tested it with a Polygon2D, a CollisionPolygon2D, and a CollisionPolygon3D; the issues occurs with all of them.  It later occurred to me that this might happen with a Curve2D as well, and it does.

![image](https://user-images.githubusercontent.com/2808851/214926182-b8609b87-85a1-4a08-8017-be4eeec912c6.png)


### Steps to reproduce

Add a node that has a Polygon or Curve resource, such as a Polygon2D, draw some points, then check the PackedVector2Array resource.

### Minimal reproduction project

N/A
if (waiting_for_first_scan) {
		waiting_for_first_scan = false;
		Engine::get_singleton()->startup_benchmark_end_measure(); 
		
		
		RenderingServer::get_singleton()->global_shader_parameters_load_settings(true);
		
		if (!singleton->cmdline_export_mode) {
			EditorResourcePreview::get_singleton()->start();
		}
		_load_docks();
		if (!defer_load_scene.is_empty()) {
			Engine::get_singleton()->startup_benchmark_begin_measure("editor_load_scene");
			load_scene(defer_load_scene);
			defer_load_scene = "";
			Engine::get_singleton()->startup_benchmark_end_measure();
			if (use_startup_benchmark) {
				Engine::get_singleton()->startup_dump(startup_benchmark_file);
				startup_benchmark_file = String();
				use_startup_benchmark = false;
			}
		}
	}
}
void EditorNode::_scan_external_changes() {