Index: wp-includes/feed-atom-comments.php
===================================================================
--- wp-includes/feed-atom-comments.php	(revision 25365)
+++ wp-includes/feed-atom-comments.php	(working copy)
@@ -12,7 +12,15 @@
 	xmlns="http://www.w3.org/2005/Atom"
 	xml:lang="<?php bloginfo_rss( 'language' ); ?>"
 	xmlns:thr="http://purl.org/syndication/thread/1.0"
-	<?php do_action('atom_ns'); do_action('atom_comments_ns'); ?>
+	<?php 
+	//duplicate_hook
+	do_action('atom_ns'); 
+	/**
+	 * Fired at the end of the Atom comments feed root to add namespaces.
+	 *
+	 * @since 2.8.0
+	 */
+	do_action('atom_comments_ns'); ?>
 >
 	<title type="text"><?php
 		if ( is_singular() )
@@ -39,7 +47,14 @@
 	<link rel="self" type="application/atom+xml" href="<?php bloginfo_rss('comments_atom_url'); ?>" />
 	<id><?php bloginfo_rss('comments_atom_url'); ?></id>
 <?php } ?>
-<?php do_action('comments_atom_head'); ?>
+<?php 
+/**
+ * Fired at the end of the Atom comment feed header.
+ *
+ * @since 2.8.0
+ */
+do_action('comments_atom_head'); 
+?>
 <?php
 if ( have_comments() ) : while ( have_comments() ) : the_comment();
 	$comment_post = $GLOBALS['post'] = get_post( $comment->comment_post_ID );
@@ -48,6 +63,7 @@
 		<title><?php
 			if ( !is_singular() ) {
 				$title = get_the_title($comment_post->ID);
+				//duplicate_hook
 				$title = apply_filters('the_title_rss', $title);
 				printf(ent2ncr(__('Comment on %1$s by %2$s')), $title, get_comment_author_rss());
 			} else {
@@ -79,7 +95,17 @@
 ?>
 		<thr:in-reply-to ref="<?php comment_guid($parent_comment) ?>" href="<?php echo get_comment_link($parent_comment) ?>" type="<?php bloginfo_rss('html_type'); ?>" />
 <?php endif;
-	do_action('comment_atom_entry', $comment->comment_ID, $comment_post->ID);
+	$comment_id = $comment->comment_ID;
+	$comment_post_id = $comment_post->ID;
+	/**
+	 * Fired at the end of each Atom comment feed item.
+	 *
+	 * @since 2.2.0
+	 *
+	 * @param $comment_id The ID of the comment being displayed.
+	 * @param $comment_post_id The ID of the post connected to the comment.
+	 */
+	do_action('comment_atom_entry', $comment_id, $comment_post_id);
 ?>
 	</entry>
 <?php endwhile; endif; ?>