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;
    }
}