How many letters of recommendation does Wharton's MBA program actually require?

If you are applying to Wharton, you only need to arrange one letter of recommendation, not two, so you can focus your energy on choosing the strongest possible recommender.

Wharton's Current Application Components

Why Choosing the Right Recommender Matters More Here

With only one recommendation carrying the full weight of that part of your application, your choice of recommender becomes more important than ever. A manager or mentor who can speak specifically and vividly about your leadership and growth will serve you far better than someone with a bigger title but limited direct knowledge of your work.

My Advice

Brief your one recommender thoroughly on your goals and the specific examples you want highlighted, rather than leaving them to write a generic letter, since you will not have a second recommendation to balance it out.