I sometimes will ask a question already answered earlier in a thread because I jumped into the thread later and simply missed the answer posted earlier.There's some good info in post 86, too.
Random thought in my head: Sometimes I wondered why some people don't read anything in a thread and keep asking questions to things that have been answered 5 different ways already. Then I realised trying to figure out illogical behaviour is illogical. Then I started ignoring people who exhibited this behaviour, once a pattern was established. For really serious offenders, there's the ignore button, too!