Duplicate indexes error in SQL

Backing up my databases today, I noticed the following errors:
The following indexes appear to be equal and one of them should be removed: comment_content, comment_content_2, and the same with post_title, post_title_2 and user_login, user_login_key. I’ve never seen these before, and they don’t exist in my other wordpress sites. Anyone have any ideas if this is an issue and if it should remove them?