An embarrassing situation early in my writing career taught me the hard way of the importance of keeping accurate records. The embarrassing situation was that I submitted an article a second time to a magazine that had recently rejected it. Now, it may not be a problem resubmitting an article to the same magazine, but one should wait a while before doing so.
Keeping accurate records is critical not only to avoiding embarrassment but to making sure you know where you sent what article or story. Knowing this will show you when to follow up, where to follow up, and how to follow up.