"user warning: Duplicate entry" when saving a configuration

When saving a configuration I get this error message:

    * user warning: Duplicate entry 'comment_form_Level00_new_unauthenticated_user_ca' for key 1 query: variable_set INSERT INTO variable (name, value) VALUES ('comment_form_Level00_new_unauthenticated_user_captcha', 's:12:\"captcha/Math\";') in /home/18358/domains/lifetwo.com/html/production/includes/database.mysql.inc on line 172.
    * user warning: Duplicate entry 'contact_mail_user_Level00_new_unauthenticated_us' for key 1 query: variable_set INSERT INTO variable (name, value) VALUES ('contact_mail_user_Level00_new_unauthenticated_user_captcha', 's:12:\"captcha/Math\";') in /home/18358/domains/lifetwo.com/html/production/includes/database.mysql.inc on line 172.
    * user warning: Duplicate entry 'contact_mail_page_Level00_new_unauthenticated_us' for key 1 query: variable_set INSERT INTO variable (name, value) VALUES ('contact_mail_page_Level00_new_unauthenticated_user_captcha', 's:12:\"captcha/Math\";') in /home/18358/domains/lifetwo.com/html/production/includes/database.mysql.inc on line 172.

I was able to manually edit the records using phpMyAdmin, so this isn't a problem for me any more.

Our other permissions levels seemed to be saved properly in the variable table.

I wonder if this one permission name -- "Level00_new_unauthenticated_user" -- is causing the problem due to its length? It's the longest of our permission names and the others save to the variables table OK. Could it cause a truncation issue --? For instance, the value "contact_mail_user_Level00_new_unauthenticated_us" is truncated from "contact_mail_user_Level00_new_unauthenticated_user_captcha."

I hope that's not a false lead, but it stood out as the only odd thing I could identify.