Database installation error

[dbembibre]

A fresh install under vb3.5 RC2

In the first step the installer say

Database error in vBulletin 3.5.0 Release Candidate 2:

Invalid SQL:
CREATE TABLE adv_gallery_categories (
catid smallint(5) NOT NULL auto_increment,
title varchar(255) NOT NULL default '',
description text,
displayorder smallint(4) NOT NULL default '0',
hasimages smallint(3) unsigned NOT NULL default '0',
active smallint(3) unsigned NOT NULL default '0',
catuserid int(10) unsigned NOT NULL default '0',
allowusercats smallint(3) unsigned NOT NULL default '0',
parent smallint(5) unsigned NOT NULL default '0',
parentlist varchar(255) NOT NULL default '',
password varchar(100) NOT NULL default '',
catimage varchar(255) NOT NULL default '',
membercat smallint(3) unsigned NOT NULL default '0',
imagecount int(10) NOT NULL default '0',
postcount int(10) NOT NULL default '0',
lastimageid int(10) NOT NULL default '0',
lastimagetitle varchar(255) NOT NULL default '',
lastimageuserid int(10) unsigned NOT NULL default '0',
lastimageusername varchar(100) NOT NULL default '',
lastimagedateline int(10) unsigned NOT NULL default '0',
lastpostid int(10) unsigned NOT NULL default '0',
lastpostimagetitle varchar(255) NOT NULL default '',
lastpostuserid int(10) unsigned NOT NULL default '0',
lastpostusername varchar(100) NOT NULL default '',
lastpostdateline int(10) unsigned NOT NULL default '0',
options int(10) unsigned NOT NULL default '0',
useroptions int(10) unsigned NOT NULL default '0',
adv_setting text NOT NULL,
disext MEDIUMTEXT NOT NULL default '',
newimageemail varchar(255) NOT NULL default '',
newpostemail varchar(255) NOT NULL default '',
PRIMARY KEY (catid),
KEY parent (parent)
) TYPE=MyISAM;

MySQL Error : Table 'adv_gallery_categories' already exists
Error Number : 1050
Date : Monday, August 8th 2005 @ 07:36:01 AM
Script : http://www.bmwfaq.com/admincp/vbagallery_install.php
Referrer : http://www.bmwfaq.com/admincp/vbagallery_install.php
IP Address : xxx.xxx.xxx
Username : xxxx
Classname : vb_database

[dbembibre]

I delete by hand all tables called adv_gallery and can install as normal.
I cant understand if i never install vbGallery how the tables exist in my database ???
Exuse my broken English

The only thing I can figure is that you may have hit the refresh button or hit the continue button more than once when trying to install.