@MattW can you please look at reply section... sometimes added code/tags duplicate itself when we post reply... specially tag of quote, spoiler, color, font, alignment and size duplicates it self after post reply...
Type in the text correctly and save it in drafts before you hit the post button (by correctly, I mean don't write quote as qoute, ["quote"[, etc). I noticed that just yesterday while doing a match presentation. Before that, the quote tag did just piss me off as whenever I used it, the post would automatically generate copies of
[/quote] at the bottom which would then mess up my whole work. Also, it is a good practice to check previews of the post you're typing.
Even though, I don't know the exact reason why posts sometime behave like that. It is just a trick I came across, you should try it once.