Minimize duplicates within data in excel by figuring out what customers are purchasing

So our system tracks individual sales and returns a lot of duplicates. I was thinking of adding in a formula that would let me know if that customer has purchased X, Y item, so that I could deduplicate by customer ID. Our tables look a little like:

I wasn't sure if I should be using a nested IF function, an X-lookup, concatenating the Customer ID and purchase? I was hoping for a formula that would either return the purchase or that would bring back a "Yes" or "No">