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It is completely normal for a paper to be published after it has been presented. In fact, most papers are.
What's generally frowned upon is presenting a paper after it's been published (the whole point is to solicit feedback in order to improve the paper prior to publication). The other MAJOR no-no is to submit the same (or very, very similar papers) to more than one journal prior to hearing back. That is, if you send the same paper at the same time to multiple generals, that's almost certainly a breach of protocol (it would probably get you barred from publishing it in either, if it were discovered). Now, if you get a rejection (or R&R, but aren't interested in doing the R&R), then you can send it out for review to another outlet. Absolutely nothing wrong with that. But you should never have the same paper under consideration at more than one publication outlet at any one time.
On the other hand, you can submit similar papers to multiple conferences (although make sure that the audience will be substantially different, otherwise you're just wasting people's time if you're presenting the same material).