A simple solution to fix this issue is to make some modifications in:
/system/library/pagination.php
Search for
| 1 2 3 4 5 6 7 8 | if ($page > 1) { 	$output .= '<li><a href="' . str_replace('&page={page}', '', $this->url) . '">' . $this->text_first . '</a></li>'; 	if($page - 1 === 1){ 		$output .= '<li><a href="' . str_replace('&page={page}', '', $this->url) . '">' . $this->text_prev . '</a></li>'; 	} else { 		$output .= '<li><a href="' . str_replace('{page}', $page - 1, $this->url) . '">' . $this->text_prev . '</a></li>'; 	} } | 
and replace with
| 1 2 3 4 5 6 7 8 9 | if ($page > 1) {            $output .= '<li><a href="' . str_replace(array('&page={page}', '?page={page}'), '', $this->url) . '">' . $this->text_first . '</a></li>';            if ($page - 1 === 1) {                 $output .= '<li><a href="' . str_replace(array('&page={page}', '?page={page}'), '', $this->url) . '">' . $this->text_prev . '</a></li>';            } else { 		$output .= '<li><a href="' . str_replace('{page}', $page - 1, $this->url) . '">' . $this->text_prev . '</a></li>';            } } | 
also find
| 1 | $output .= '<li><a href="' . str_replace('&page={page}', '', $this->url) . '">' . $i . '</a></li>'; | 
and replace with
| 1 | $output .= '<li><a href="' . str_replace(array('&page={page}', '?page={page}'), '', $this->url) . '">' . $i . '</a></li>'; | 
Source: http://forum.opencart-russia.ru/threads/oshibka-paginacii-page-page-pri-seo.4583/
