Problems with indexes of sql table

[JohnnyTheOne]

I have Checked my sql tables in phpmyadmin Then did I get this report?

Problems with indexes of table `phpbb_attachments`
Warning More than one INDEX key was created for column `attach_id`

Problems with indexes of table `phpbb_digest`
Warning PRIMARY and INDEX keys should not both be set for column `user_id`

Problems with indexes of table `phpbb_pa_comments`
Warning PRIMARY and INDEX keys should not both be set for column `comments_id`

Problems with indexes of table `phpbb_sessions`
Warning PRIMARY and INDEX keys should not both be set for column `session_id`

I also get the same report on 2 other sites. this is normally or is this a bug?

who can explain this

Thanks in advance