If you are trying to get several magazines to publish a short story or article and say three of the magazines want to pay you for the story, can you sell to all three? Is it legal? Even if you were receiving no money, cay more than one magazine publish the writing?
It's not illegal to send the exact same article to several magazines, but it's VERY poor form. You need to tell each editor that you have also sent the piece to other publications, and let them make the call. Most will not publish something that has been published or accepted for publication elsewhere.