Yes, I manually place my tags, writing them in BBcode myself, not even via editors, simply by typing it using the keyboard. I also always end the tags in the reverse-order that I made them in, so they are neat, and less buggy, it still happens despite all of this.
Example:
Code:
[spoiler]
[align=center] [color=#555555] [b]
Whatever I want to say..
[/b] [/color] [/align]
[/spoiler]
Ah yes, I now remember what it does, sometimes it creates a duplicate spoiler to one I already have, and usually a line or two down, despite there not being multiple tags to have a spoiler of that name, idk where the duplicate ever comes from.