You can clone with
No one assigned
Search for: _s
Replace with: Underscores
then upload it
when i tried to use it : Fatal error: Call to undefined function registerunderscoresidebar() in /home/membagi/public_html/wp-content/themes/Underscores/functions.php on line 93
It looks like you searched for _s without a space before the underscore in your last search.
thanks ian, i didn't see there is a whitespace on it :)