Comments to Custom Post Type

I’m switching to a new theme which uses the custom post types: Question (as posts) and Answer (as comments to posts). I have converted current Posts into Question using a plugin.
Now, I have to convert comments (of each post) to Answer which will be relate to each (converted) Question.

I used the following code but although all comments converted and created the right relation to each question, I finally got multiple answer depending on how many comments where in each post. To be more clear, if a question had 5 comments before, now I have 5×5=25 answers. The code actually inserted the answers 5 times instead of just 1.

I think that the problem is in the foreach loop. Can you please help how should I modify the code to avoid this problem?

$args = array(
'posts_per_page' => -1,
'post_type' => 'thread'
);
$threads= get_posts( $args ); // Get all posts of thread.
foreach($threads as $thread):
$comment_args= array(
'post_id' => $thread->ID
);
$thread_comments= get_comments($comment_args); // Get all comments of the post.
foreach($thread_comments as $thread_comment):
$reply_post= array(
'post_status' => 'publish', // Set replies status.
'post_type' => 'answer', // Set post type, post type must be answer.
'post_parent' => $thread->ID // Set id of question to make relation between question and answer
'post_author' => $thread_comment->user_id, // Set comment user id as post id.
'post_title' => 'RE: '.$thread->post_title, //They prefix RE: to every reply so i think we might be do the same.
'post_content' => $thread_comment->comment_content // Set comment content as post content.
);
wp_insert_post($reply_post); // Insert the comment as post having post type replies.

endforeach;
endforeach;

Please try:

$args = array(
    'posts_per_page' => -1,
    'post_type' => 'thread'
);

$thread_posts = get_posts( $args ); // Get all posts of thread.

foreach($thread_posts as $thread_post_object) {

    /*not sure really need to be working IDs only, but is simpler, plus made checking was getting right ones easier */
    $thread_post_IDs[] = $thread_post_object->ID; 

}

foreach ($thread_post_IDs as $thread_post_ID) {


    $comments_query = new WP_Comment_Query;
    $thread_comments = $comments_query->query(array 
        (
            'post_id' => $thread_post_ID,
            'status' => 'approve'
        )
    );

    foreach ($thread_comments as $thread_comment) {
        $reply_post = array(
            'post_status' => 'publish', // Set replies status.
            'post_type' => 'answer', // Set post type, post type must be answer.
            'post_parent' => $thread_post_ID, // Set id of question to make relation between question and answer
            'post_author' => $thread_comment->user_id, // Set comment user id as post id - requires registered users otherwise returns 0
            'post_title' => 'RE: ' . get_the_title($thread_post_ID), //since have ID only need alternative way to get title
            'post_content' => $thread_comment->comment_content // Set comment content as post content.
        );

        //print_r($reply_post); // if you want to test it first
        wp_insert_post($reply_post); // if you want to see what happens!

    }

}