how to filter post by post title

I have a problem on my site. i have a automatic posting by instagrate the problem is sometimes my post gets duplicate. i want to filter my posts by their post title.

i have this setup on page to display all posts.

<div class="container"> <div class="row">
	<div id="primary" class="content-area col-md-8">
		<main id="main" class="site-main" role="main">

		<?php if ( have_posts() ) : ?>

			<?php /* Start the Loop */ ?>
			<?php while ( have_posts() ) : the_post(); ?>

				<?php
					/* Include the Post-Format-specific template for the content.
					 * If you want to overload this in a child theme then include a file
					 * called content-___.php (where ___ is the Post Format name) and that will be used instead.
					 */
					get_template_part( 'content', get_post_format() );
				?>

			<?php endwhile; ?>

			<?php bootstrap_pagination();?>

		<?php else : ?>

			<?php get_template_part( 'no-results', 'index' ); ?>

		<?php endif; ?>

		</main><!-- #main -->
	</div><!-- #primary -->

<?php get_sidebar(); ?>
</div></div>