Index: wp-admin/post-new.php
===================================================================
--- wp-admin/post-new.php	(revision 19374)
+++ wp-admin/post-new.php	(working copy)
@@ -22,11 +22,14 @@
 	$parent_file = 'edit.php';
 	$submenu_file = 'post-new.php';
 } else {
-	if ( isset( $post_type_object ) && $post_type_object->show_in_menu && $post_type_object->show_in_menu !== true )
+	$submenu_file = "post-new.php?post_type=$post_type";
+	if ( isset( $post_type_object ) && $post_type_object->show_in_menu && $post_type_object->show_in_menu !== true ) {
 		$parent_file = $post_type_object->show_in_menu;
-	else
+		if ( ! isset( $_registered_pages[ get_plugin_page_hookname( "post-new.php?post_type=$post_type", $post_type_object->show_in_menu ) ] ) )
+			$submenu_file = $parent_file;
+	} else {
 		$parent_file = "edit.php?post_type=$post_type";
-	$submenu_file = "post-new.php?post_type=$post_type";
+	}
 }
 
 $title = $post_type_object->labels->add_new_item;