Removing the extra 0 from blog URLs?

Well, that’s how WordPress will build permalinks by default. So your new site is structuring them as is default.
If your old site was not structuring them this way (not appending zero’s), then that is of interest.

Anyways, you could follow the instructions on this link to get this done:
https://wordpress.stackexchange.com/questions/65546/removing-leading-zeros-from-custom-permalink-structure

function t5_strip_leading_zeros_in_url( $url )
{
    // no pretty permalinks
    if ( ! $GLOBALS['wp_rewrite']->get_month_permastruct() )
    {
        return $url;
    }

    return str_replace( '/0', '/', $url );
}
add_filter( 'month_link', 't5_strip_leading_zeros_in_url' );
add_filter( 'day_link',   't5_strip_leading_zeros_in_url' );
add_filter( 'the_permalink', 't5_strip_leading_zeros_in_url' );