updatedb failed for drupalchat while upgrading from 6.x-2.0-beta20

I'm upgrading a site to D7. I get this error when I upgrade:

drush updb

The following updates are pending:

drupalchat module :
7000 -
7001 -

Do you wish to run all pending updates? (y/n): y
Cannot add index <em class="placeholder">uid</em> to table <em class="placeholder">drupalchat_users</em>: index already exists. [error]
Performed update: drupalchat_update_7000 [ok]
Finished performing updates. [ok]
updatedb failed for drupalchat [error]

Setting priority to critical since this don't let you upgrade between versions.