get_termsとget_postsの入れ子例 改（複数タームに属する記事は2回登場しないように）

archive-faq.php

<?php
	$displayed_post_id = array();
	$terms = get_terms(
		'faqcategory', array(
			'orderby'  => 'slug',
			'order'    => 'ASC'
		)
	);
	foreach( $terms as $term ):
?>
	<?php
		$cat_posts = get_posts( array (
				'taxonomy'        => 'faqcategory',
				'term'            => $term->slug,
				//'category_name' => $term->slug, /* カテゴリーの場合 */
				'post__not_in'    => $displayed_post_id
			)
		);
		if( $cat_posts ):
	?>
		<h2><?php echo esc_html( $term->name ); ?></h2>
		<ul>
		<?php
			foreach( $cat_posts as $post ): 
			setup_postdata( $post );
		?>
			<li><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></li>
		<?php 
				$displayed_post_id[] = $post->ID;
				endforeach; wp_reset_postdata();
		?>
		</ul>
	<?php endif; ?>
<?php endforeach; ?>