Things like duplicate post can happen especially if your internet connection suddenly stopped or become unstable and when you want to submit your post the forum goes blank or you get error message such as 502 or 504 or Network problem. When this thing happen DO NOT RELOAD the page immediately. Instead, copy the thread's web address and then go to that thread to see whether your post has been submitted or not.
Why do this?
Because when you try to submit a post and then your internet got disconnected/become unstable/get 502/504/Network problem there is a chance that your post already reach the server but the page fail to open. For example:
You tried to submit your post by clicking at 10:40:20 AM
your post reached the server at 10:40:22 AM
internet got disconnected at 10:40:23 AM
page fail to load at 10:40:24 AM
reload at 10:41:30 AM
duplicate post reach the server at 10:41:31 AM
BAN from moderator reach your profile at 12:45 AM LOLS
So the solution for this kind of problem are:
1. don't reload the page but rather just open a new tab and then go to the thread where you want to submit your post and check first. If your post is already posted on the thread then you can avoid violating the forum rules (regarding duplicate post).
2. Or you can just press the "Back" button on your browser and then reload the page and if you see that your post is visible then you can avoid submitting a duplicate post.
However, if you mistakenly do this mistake then you can do one of these things:
1. delete the post by yourself. This is the easiest thing to do but you can only modify or delete the post up until 1 hour after you submit the post (you can check the time of your post just above your avatar on your post box). After 1 hour you will not be able to modify/delete it anymore.
2. if 1 hour have passed you must contact a moderator and ask him/her to delete the post for you.
3. if you got a ban before you or a moderator can delete the post then please go to the moderator who gave you a ban and tell him/her about the mistake and he will consider your case and if he judge that you are right then the ban/warning will be withdrawn. If you do not know who banned you then you can still contact any moderator and we will check your case for you.
I hope you can avoid this kind of mistake in the future.