Removing duplicate values from an array in PHP by using array_unique(), this will return a new array, based on the input without duplicate values.

The second parameter is sort type, default is SORT_STRING.

• SORT_REGULAR Compare items normally without changing type.
  
• SORT_NUMERIC Compare items numerically.
• SORT_STRING Compare items as strings.
• SORT_LOCALE_STRING Compare items as strings, based on the current locale.

An example of array_unique:

$items = array('Apple', 'Orange', 'Lemon', 'Lime', 'Orange', 'Peach', 'Pear', 'Mango', 'Peach');
$remove_dupes = array_unique($items);
echo json_encode($remove_dupes);

This will output:

{
  "0": "Apple",
  "1": "Orange",
  "2": "Lemon",
  "3": "Lime",
  "5": "Peach",
  "6": "Pear",
  "7": "Mango"
}

The duplicated values (Orange and Peach) only exist once now.