WordPress Custom Theme: My site shows the same posts on Page 1 and Page 2 and so on [duplicate]

You need to pass posts_per_page and paged param.

    $args = array(
      'post_type' => 'nutrisense_nieuws',
      'posts_per_page' => get_option('posts_per_page'); // number of posts to show per page  
      'paged' =>  get_query_var( 'paged', 1 ) // get page if set else page 1, Use "page" for static front page instead of "paged" see the links. 
    );

    $the_query = new WP_Query($args);

Check these first

Get Query Var

WP Query