When's it OK to write a similar story for two publications?

I was recently asked to write a short article about someone for a local publication. I spent way more time interviewing the subject than necessary given the length of the article I've been asked to write (my mistake), so I'm hoping to make up for that by selling a story to another magazine.

What's the etiquette on this? The magazine I'm writing for is a general interest local publication. Say the guy's a chef - would it also be OK to pitch the story to a food magazine? I know people who will write the same story for magazines in different countries, but what about magazines distributed in the same market, but one's general and one's specific?

Thanks!