We are not exactly sure what causes this to happen but it comes and goes so it seems to be related to network issues.Mike343;608512
I found when you reply to a thread, once your reply is typed and you have clicked on SUBMIT REPLY ONCE, if you click on the link to the thread located on red bar above, only one reply is shown.
on the red bar, in this case, says Thread: Replies are messed up, with the thread name being a url. if we all would do this, double posts wont happen.
Be sure to only click submit reply once and either click the forum name where i specified, or click USER CP.