Pagination is not working correctly there is this wierd looping

I have never seen this issue. without seeing the code that your developer wrote there isn’t much to say here. Did he use a custom query to get the information from the database? Did he rewind the posts? Does he have the code for pagination in the template twice? which actually could be the case here. I have seen in wordpress templates where the code for the pagination is at the top of the page as well as the bottom of the page. If that is the case then all he would need to do is remove that code. The code would look something like this

<?php previous_posts_link("Last Page"); ?> | 
            <?php next_posts_link("Next Page"); ?>

Yours could be different.