Query seems to be duplicated

Your queries are showing the same output, because they are identical

Here is your first queries arguments:

$args = array(
    'orderby' => 'title',
    'order' => 'ASC',
    'posts_per_page' => 5,
    'paged' => get_query_var('paged'),
    'tax_query' => array(
        array(
            'taxonomy' => 'store-category',
            'field' => 'id',
            'terms' => array($_POST['region'])
        )
    )
);

Here is your second queries arguments:

$args = array(
    'orderby' => 'title',
    'order' => 'ASC',
    'posts_per_page' => 5,
    'paged' => get_query_var('paged'),
    'tax_query' => array(
        array(
            'taxonomy' => 'store-category',
            'field' => 'id',
            'terms' => array($_POST['region'])
        )
    )
);

You ask for the same thing both times, you get the same thing both times.

Since you’re using ACF you should query by the post meta for your ACF field:

e.g. something similar to this:

$args = array(
    'meta_key' => 'premium', // I guessed your field would be called premium, but this might not be the case
    'meta_value' => 'yes'
);

// get results
$the_query = new WP_Query( $args );

... etc..


$args = array(
    'meta_key' => 'premium',
    'meta_value' => 'no'
);

// get results
$the_query = new WP_Query( $args );

ACF fields are post meta/custom fields too, they’re just wrapped behind a fancy UI/API