Welcome to the forum, James.
I've enjoyed that very dish many times at Perkins. It's never struck me that I might be able to claim both hash browns and breakfast potatoes (the hash browns are better anyway).
It's pretty obvious to me that the phrase 'with hash browns, breakfast potatoes or fruit' means that you choose one of the three, just as 'white, whole wheat or rye toast' means you choose one of those three.
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