Editor: Fix `Paste From Clipboard` make two root separate scenes pointing to same file

editor/scene_tree_dock.cpp

@@ -3217,6 +3217,7 @@ List<Node *> SceneTreeDock::paste_nodes() {
 		if (!paste_parent) {
 			paste_parent = dup;
 			owner = dup;
+			dup->set_scene_file_path(String()); // Make sure the scene path is empty, to avoid accidental references.
 			ur->add_do_method(EditorNode::get_singleton(), "set_edited_scene", dup);
 		} else {
 			ur->add_do_method(paste_parent, "add_child", dup, true);