Wrong. Double posting and tripple posting, in some instances, are ok. This is if you are replying to different people in each post. If your only replying to yourself, then that's against the rules. If you also post twice in response to the same post, that is also against the rules.
Now, I'm not a grammar Nazi by any means, but when you rag on someone, and call them young due to their usage of English, at least use proper English yourself.