It looks like the "Quick Reply" pop up window is not clearing the content and resetting the way it should when you post.
If you want to avoid double posting, keep an eye on that window when you click the "Reply" button.
As soon as you see the "Reply" button become active again, CLOSE THE POP UP WINDOW.
That should prevent the system from attempting an automatic resubmit.
This worked for me a little earlier.
I am using a PC with a normal web browser.
Probably not helpful to mobile phone users.
Hope this works and is helpful.
If you see this post twice, I am probably wrong.