wondering...
 

if i post something, then see something that someone else wrote right before that, if i quote that person, is that a violation of the rules since i posted twice one right after the other?

Yes, When that happens I generally edit my previous post with something to the effect of
[edit]@username - my response.

Or you could hit the quote button under their post copy what they wrote, quote tags included, and edit it into your previous post with your response...or just wait for someone else to post .

wow, ok, can you delete your own threads? so that i can fix it? if it happens again?

No, you cannot delete your own thread, but you can ask a moderator to lock it for you.

If you accidentally double-post, just report the accidental post and ask moderators to merge it for you with your previous (or if it's a server glitch and it's the exact same post, they'll just delete it for you). :) If you report the post yourself, you won't get into trouble for it. :) Mistakes happen and we know that. :3 (Also note that if you double-post because of a server glitch you won't be punished for that at all even if you didn't see and realize and report it.)