Hello and thanks for your question.

I don't regard this as a problem. If you're writing about a significant professional experience, especially if it's an achievement or demonstration of growth, it's only natural that your recommender would also talk about it. In fact, it might seem odd if they didn't.

You're right to keep in mind the need to show range across the application as a whole though. You shouldn't be using one experience as the basis for more than one essay, and your recommenders should highlight a number of examples of things that you've done.

Hope this helps.

Helen