What you need to do is collect a list of posts, making sure you don’t have duplicates in the first loop and then show them in a different loop.
so, in your nested loop
if($items) {
$collected_artists= array();
foreach ($items as $item) {
// see if we already have this one
if (!is_array($item->ID, $collected_artists)) {
// don't have it, add to list
$collected_artists[] = $item->ID;
}
} // end foreach $item
} // end if items
// Loop over $collected artists and show data for each
if ($collected_artists) {
foreach ($collectec_artists as $artist_id) {
// etc...
}
}
