Something

<?php

class EDM_Validate_mustMatch extends Zend_Validate_Abstract
{
	const NOT_MATCH = 'notMatch';

	protected $_field;

	protected $_messageTemplates = array(
		self::NOT_MATCH => 'Values do not match'
	);

	public function __construct($field = null)
	{
		if (null === $field) {
			require_once 'Zend/Validate/Exception.php';
			throw new Zend_Validate_Exception("Nothing specified for mustMatch Validator");
		}
		$this->_field = $field;
	}

	public function isValid($value, $context = null)
	{
		$value = (string) $value;
		$this->_setValue($value);

		if (is_array($context)) {
			if (isset($context[$this->_field])
				&& ($value == $context[$this->_field]))
			{
				return true;
			}
		} elseif (is_string($context) && ($value == $context)) {
			return true;
		}

		$this->_error(self::NOT_MATCH);
		return false;
	}
}