Loop multiples sans posts dupliqués

#loopofdeath

<?php 
						$postsInCat = get_term_by('name','themes','category');
						$postsInCat = $postsInCat->count;
						//variable avec le nombre total de posts
						$limite = 15;
						$limitwhile = intval($postsInCat/$limite);
//echo $limitwhile;
					?>	
					<!--premiere loop-->
					<?php 
							$do_not_duplicate = array(); 
							$i= 1;
							  while($i <= $limitwhile) {
						?>
								  <?php   $mosaics = new WP_Query(array('category_name'=>'themes','posts_per_page'=> 15, 'post__not_in' => $do_not_duplicate ) ); ?>
								  <?php	if ( have_posts() ) :?>
										<?php echo '<li id="contenu'.$i.'" class="leflah">'?>
											<?php   while ($mosaics->have_posts()) : $mosaics->the_post(); ?>
											<?php   $do_not_duplicate[] = $post->ID; ?>
												<a href="<?php the_permalink();?>">
													<?php the_title(); ?>
												</a>
											<?php endwhile; ?>		
										<?php echo '</li>'?>
								<?php else :?>
									<!--ne rien afficher-->
								<?php endif; ?>
								<?php wp_reset_postdata(); 
						  		?>
						<?php
							$i++;
							}
						?>