When Cloning Zend_Form, the Id will not be updated thus causing ID Collisions.

Example:

$test = new Zend_Form();
$test->addElement('text', 'foo');

echo $test;

$new = clone $test;
echo $new;

Produces:

Recommend work around is to have a counter that will increment when the __clone method is called. Zend_Form should then append that number to the id:

class Zend_Form
{
    protected static $_cloneCount = 0;

    // ..snip ..
        public function __clone()
    {
        self::$_cloneCount++;
        $elements = array();
        foreach ($this->getElements() as $name => $element) {
            $element = clone $element;
            $newId  = $element->getId() . '-' . self::$_cloneCount;
            $element->setAttrib('id', $newId);

            $elements[] = $element;
        }
        $this->setElements($elements);
    
        //duplicate below for display groups and subforms
    }

}