Unable to upgrade to 7.x-2.0-beta3 from 7.x-1.3

Hello,

I tried upgrading to the latest beta of 2.0, but when I run update.php I get this error:

Update #7200
Failed: PDOException: SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry 'thumbnail' for key 'machine_name': INSERT INTO {breakpoint_group} (machine_name, name, breakpoints, type) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3); Array ( [:db_insert_placeholder_0] => thumbnail [:db_insert_placeholder_1] => thumbnail [:db_insert_placeholder_2] => a:4:{i:0;s:26:"custom.user.update.default";i:1;s:25:"custom.user.update.narrow";i:2;s:25:"custom.user.update.normal";i:3;s:23:"custom.user.update.wide";} [:db_insert_placeholder_3] => custom ) in drupal_write_record() (line 7013 of /var/www/clients/client2/web2/web/includes/common.inc).

I followed the instructions on the module page to upgrade:

Disable Responsible images and styles (do not uninstall)
Download Breakpoints, CTools and Field formatter settings.
Enable Responsible images and styles again (along with its requirements Breakpoints, CTools and Field formatter settings).

But, like I said, I get that above error.

Any ideas what may be wrong?

Thanks!