Para poder usar array_unique() primero debes agrupar los elementos en común, así:
Código PHP:
Ver original$list = [
['x' => 'a', 'y' => 1],
['x' => 'b', 'y' => 2],
['x' => 'a', 'y' => 3],
];
$groups = [];
foreach ($list as $object) {
foreach ($object as $key => $value) {
if (!isset($groups[$key])) { $groups[$key] = [];
}
$groups[$key] []= $value;
}
}
foreach ($groups as $key => $group) {
}