<?php

function array_remove_unique(array $array) {
	$tmp = [];
	foreach($array as $item) {
		if(isset($tmp[$item])) {
			$tmp[$item] += 1;
		}
		else {
			$tmp[$item] = 1;
		}
	}

	$array = [];
	foreach($tmp as $key => $value) {
		if($value > 1) {
			$array[] = $key;
		}
	}
	return $array;
}

$array = [1,1,2,3,4,2,5];
print_r($array);
print_r(array_remove_unique($array));