A long time ago (but in this galaxy), I came in the top three of a writing contest, and was invited to the Award Ceremony. It was a great event, and I swapped notes with the other writers, judges, and authors. The person who won first prize told me that the same story had also won first prize in another contest - in fact, I later discovered it had won first prize in three competitions that summer! Obviously an excellent story :) Interestingly, as an entrant to the same three contests, I also knew that each of the competitions had a rule that said they would only accept previously unpublished stories AND two of the contests had a specific rule that said your story could not be currently entered into any other competitions, while the other had a rule which stated that if you won, you had to notify the judges so they could take your entry out of their contest. As far as I know, nobody ever raised a fuss, and the writer escaped with three wins. It did make me very sensitive to rules though, and I began to pay close attention to them. It seems to me you can sail pretty close to the wind, and still be 'legal'. I've heard various opinions from different writers though, including those that blatantly ignore the rules, through to those that religiously follow not just the letter but the spirit of the rules too.
Here are a few slippery ways I've heard of people entering contests:
1. When it says the story can't be entered in another contest... it says nothing about not being submitted to a magazine for publication (as long as that's an open submission window, not a contest).
2. If there's a date cut-off, 'Story must not have been entered into a contest before 30 Jun 2017', you can juggle dates to ensure you enter stories a day or two apart, and squeeze them into contests (e.g. if the other contest has a 15 Jul cut-off, make sure you enter in July even if they accept pieces from May)
3. What classifies as 'the same' story? If the story has been substantially edited (e.g. cut from a 2500 word piece to a 2000 word version), is it the same story?
4. Changing the story title. It may have the same text (or be edited as in 3 above), but if you change the title, it will only really be noticeable if/when the story is published in full. This is a good option, until you win...
I'm sure there are other options here (like lying). As writers, we want to maximise the chance of our story being published, and I understand the compulsion to sail close to the wind. From a contest organiser's perspective, it is frustrating to be in the final throes of selecting a winner to have the writer pull the plug and tell you the story has/is/will be published elsewhere, or (even worse) needs to be withdrawn.
I'm interested to know what other writer's do about this dilemma. Feel free to share your thoughts, anonymously if necessary! Incidentally, you don't need to worry about our contests - we allow simultaneous entries, and previously published pieces (as long as you still own copyright). We do ask that you let us know if you win a contest with a story currently in our system. Sometimes, this is not a problem and the other organiser is open-minded too (just like the Brighton Prize last year, where we both published a story). We do need to know, and generally will be delighted for you.