Coming to this discussion late. Interesting. I was worried when I revised a poem AFTER publication, and it turned into a completely different poem (even though it kept the same title and certain other elements), and it got published in a second journal. Nothing happened. All was fine. So far....

Re: simultaneous submissions. I tend not to do them, but I've been "trained" that way. I actually believe that, in this century, there's no reason whatsoever to NOT submit simultaneously. I'm annoyed by journals that state that they won't consider simultaneous submissions, especially those that don't reply for months or years, or never reply! No one applies for a single job, waits a year, gets a rejection letter (if they're lucky), and then applies for a second job.... Writers need to understand that editors are swamped, but editors also need to understand that writers are waiting, waiting, waiting. Tim Green of Rattle has the right philosophy.

I also get annoyed when journals, in this century, don't take online submissions. But that's another story....