For a Magento 1.x compatible version please see http://www.magentocommerce.com/magento-connect/same-order-invoice-number-by-fooman.html (currently not available via github)
For a Magento 1.x compatible version please see http://www.magentocommerce.com/magento-connect/same-order-invoice-number-by-fooman.html (currently not available via github)