How can I duplicate a Magento product by product id programmatically
You can call Magento’s product object’s method – “duplicate()” to duplicate the Magento product
$id = 1;
$product = Mage::getModel('catalog/product')->load($id);
$clone = $product->duplicate();
$clone = $clone->load( $clone->getId() );
$clone->setSku( 'newsku' );
$clone->save();