Error on install

I tried to install the gallery theme and I got this error

Fatal error: Cannot redeclare bp_dtheme_ajax_querystring() (previously declared in /nfs/c09/h03/mnt/137090/domains/domain.com/html/wp-content/themes/gallery/_inc/ajax.php:17) in /nfs/c09/h03/mnt/137090/domains/domain.com/html/wp-content/plugins/buddypress/bp-themes/bp-default/_inc/ajax.php on line 81