could be plugin or theme related
try
Plugins
Deactivate all but bbpress and see if this fixes. if it does, re-enable one at a time to see which is causing the error.
Themes
If plugins don’t pinpoint the problem, switch to a default theme such as twentytwelve, and see if this fixes.
This is currently how bbPress works if you have ‘revisions’ enabled each time a topic or reply is edited a new log entry will appear as per your image.
We have a ticket somewhere in Trac to update this similar to the UI experience for WordPress post or page revisions, I just kind find it right at this minute 😉
Edit: Oops, your are displaying twice, give what Robin wrote above a try 😉
